Caulking probably won't help much. Silicone is the wrong kind of caulk to use anyway, so use some polyurethane or similar instead if you do try to seal the leak with caulk.
Water is probably getting behind the siding or flashing above the leak area, and not able to find the correct path out. A better solution than caulking would be to find the fault that is letting the water in. Look for exposed nails, unflashed areas, flashing not overlapping correctly, cracked siding, that sort of thing. Clumps of moss or other debris can also cause this.
The best solution is to shingle the siding, flashing and roofing so that water finds an outside path via gravity. Where wind is also a problem, You might have to also use caulking, but doing so can cause dams that actually cause problems.