Dr. John-Mark Staude reports

RIVERSIDE RESOURCES AND QUESTCORP PREPARE PHASE 2B EXPLORATION DRILL PROGRAM AT LA UNION PROJECT, SONORA

Riverside Resources Inc.'s next phase of drilling at the La Union project in Sonora is fully financed and planned to begin soon. The rainy season has ended, and road work and drill pad construction are under way to prepare for the program. Riverside is the operator, and Questcorp Mining Inc. is the option partner (see news release dated May 6, 2025). The new phase 2B program is planned to use reverse circulation (RC) drilling. RC drilling can advance holes faster than core drilling and collects larger sample volumes. Core drilling so far has not intersected water, so the RC holes can likely be drilled mostly dry, which may improve speed and cost-efficiency. The program will mainly target Luis Hill and the Union mine. Phase 2A core drilling, with results reported on Sept. 9, 2026, intersected gold mineralization at Union and the Union mine. Phase 2B will build on those results at the Union mine and will test the sediment-hosted gold mineralization and the IP conductor unit at Luis Hill.

Immediate work on road access, logistics, field sampling and target review is progressing, and phase 2B is expected to begin in November, 2026.

Phase 2B planned actions:

• Approximately 600 m of RC drilling planned in two holes of approximately 300 m each;
• Luis Hill: one hole to test the induced polarization (IP) chargeability anomaly extending over one kilometre along strike, which coincides with the sediment-hosted gold mineralization identified in phase 1 drilling and remains open along strike and at depth;
• Union mine: one hole to follow up on a projected extension of the structure where chip-channel sampling yielded 20.2 grams per tonne gold and 226 g/t silver with 2.7 per cent zinc in 30-metre-long continuous from the Union mine (Jan. 22, 2026, news release);
• Change in drilling method: RC drilling is intended to increase penetration rates and improve access to targets at depth and will be evaluated as a more cost-effective method for future drill programs at Union;
• Drilling managed by Riverside as operator, with exploration financed by Questcorp under the option agreement.

"The phase 2A exploration program outlined a large IP target at Luis Hill and continuity of mineralization at Union. Phase 2B plans to test both of these targets with RC drilling. We expect RC drilling to advance more efficiently through the faulted ground encountered during core drilling. If the RC drilling performs as planned, it will give us a more cost-effective way to drill at Union and provide the option to run larger programs in the future," said Dr. John-Mark Staude, president and chief executive officer of Riverside Resources.

Change to RC drilling

Seven diamond drill holes totalling 530.1 metres were completed during phase 2A. Significant faulting within the targeted formations slowed core drilling and limited progress and recovery in several holes, and hole UND26-018 at Luis Hill was terminated at 70 m before reaching its planned 150-metre target depth. RC drilling is intended to increase penetration rates and improve access to priority targets while preserving the option to use diamond core where detailed geological information is required. Results from phase 2B will be used to assess the use of RC drilling in future programs at the project.

Luis Hill target

Luis Hill hosts sediment-hosted gold mineralization identified in the upper part of the Clemente formation during phase 1 drilling (see news release dated Jan. 22, 2026). Riverside's geology team has mapped the stratigraphy and structure northward for over two kilometres and identified crosscutting feeder structures as targets. The IP survey completed in phase 2A 2026 delineated a chargeability anomaly at Luis Hill extending over one kilometre along strike that coincides with the sediment-hosted gold mineralization from phase 1 and remains open along strike and at depth. Phase 2A hole UND26-018 was drilled above the anomaly but did not reach target depth. The phase 2B drilling is planned to test a geophysical anomaly with a near-vertical, 350-metre-deep drill hole.

Union mine target

Phase 2A hole UND26-013 at the Union mine intersected the continuity of the historic Sproul manto mine near the past underground mining, with anomalous lead and zinc values indicating proximity to the replacement body. Similarly, rock-chip channel sampling returned 30 metres grading 20.2 g/t Au and 226 g/t Ag along the access wall to the upper part of the Union mine. The structure is hosted in the Clemente formation, a major CRD host unit, with potential for sediment-hosted gold in the reactive shales above and below the host carbonate. The phase 2B drilling in the Union mine target is planned to test the continuity of the structure at an 80-metre stepout along strike, supported by the ground magnetic geophysics of the project.

Qualified person and quality assurance/quality control

The scientific and technical data contained in this news release pertaining to the project was reviewed and approved by Julian Manco, PGeo, a non-independent qualified person to Riverside Resources, who is responsible for ensuring that the information provided in this news release is accurate and who acts as a qualified person under National Instrument 43-101, Standards of Disclosure for Mineral Projects.

About Riverside Resources Inc.

Riverside is a well-financed exploration company driven by value generation and discovery. The company has a solid balance sheet with no debt and fewer than 95 million shares outstanding with a strong portfolio of gold-silver and copper assets and royalties in North America. Riverside has extensive experience and knowledge operating in Mexico and Canada and leverages its large database to generate a portfolio of prospective mineral properties. Riverside has properties available for option, with information available on the company's website.

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