Commercial peanut butter works best in this recipe. Natural peanut butter will leave you with a drier, crumblier cookie.
The all-purpose gluten-free flour mix that I use is from Cybele Pascal. It is as follows: 4 cups superfine brown rice flour, 1 1/3 cups potato starch (not flour), 2/3 cup tapioca starch.
Adapted from The Art and Soul of Baking by Cindy Mushet