Rough Rock works very simply. Mix one part Rough Rock powder with one part Vintage chalk paint and pat this mix with a (disposable) brush on the surface.
You see fast results and will notice that the mix produces a stone structure. The best thing is to work with two or three colors. For example, for a real stone look choose 100 ml French Gray and 100 ml Graphite. Mix 1: 1 with Rough Rock powder and apply. If the mix is too hard or too thick, dilute with a little water.
Allow to dry and then sand back the hardened buds. Instructions here.