Skin tone food coloring

Naturally it depends on what you mean by skin tone. If you're wanting to create a Caucasion-type color in, say, frosting for a cake, you might try adding a drop of both yellow and orange food coloring to a canister of white frosting. If it isn't pink enough for you, you might add a drop of red food coloring. If you're looking to make a more brown colored frosting, you could add a couple of drops of both green and red food coloring to the white frosting (or just use chocolate).