I didn't see it covered under the topic "Rock throwing," so I figured I would ask here?
It doesn't seem that "rock throwing" under RAW has a built in chance to knock someone down. If I giant throws a medium sized rock at a medium sized creature, it just hits and deals damage normally, with no other effect.
Although I certainly could be wrong.
My question is, if you would house-rule something to that effect, how would you go about it? I would love to have a monster throw things with the goal of knocking players prone. Reflex save based on damage?