Use two cups of gluten-free all purpose flour and a tablespoon of tapioca starch or tapioca flour. You can also add 1/2 tsp of xanthan gum, if the flour doesn't already have some added to it. Proceed with making the dough as instructed. You might need more milk, because gluten-free flours tend to be thirstier. Once you have a dough, pat it into a circle half-inch thick on a floured surface using your hands, not a rolling pin. Bake the biscuits for 18 minutes. They won't be as golden-brown as biscuits made with all-purpose flour, but they will taste amazing.