Last I remember, you need a skinning knife and after a player does, you can scroll wheel to harvest them. This will “execute” them and give you a charge. You have to be a decent distance away from any major city. You cook them on a fire and sell them to wongs.
I haven’t done this in so long but if you’re looking to do it for money. Not completely worth it since you can only harvest I think once an hour. Might have been changed since.