If any Hobbit stooped for a stone, it was well to get quickly under cover, as all trespassing beasts knew very well.
With a sudden flick, quick as lightning, an apple left his hand and hit Bill square on the nose. He ducked too late, and curses came from behind the hedge. ‘Waste of a good apple,’ said Sam regretfully, and strode on.
—The Fellowship of the Ring
I don’t see any explicit rules for throwing rocks or stones (or apples), but I gather it would be handled as follows:
Weapon Class: Thrown Projectiles
Fumble: 01-06 or 01-05
Attack Size/Type: Small Crush
Range Increment: 5'
Point Blank: +0
Point Blank Range: —
If someone more knowledgeable could double-check this, I’d appreciate it!
(https://philipsokolov.com/images/stone1.png)
(https://philipsokolov.com/images/stone2.png)