Oh soooo delicious biscuits. The technique is key.
The original recipe comes from Alton Brown at http://www.foodnetwork.com/ under "Alton Brown Southern Style Biscuits". There is a video on there you can watch to see exactly how they make them. The only thing different is that I have swapped out the flours and added xantham gum.
1C GF Flour (6 parts Rice Flour, 2 parts Potato Starch, 1 part Tapioca Flour)
4t Baking Powder
1/4t Baking Soda
3/4 t Salt
1t Xantham Gum
1C Buttermilk chilled (or I used 1C 1% milk with 2t cider vinegar)
Preheat oven to 450 degrees.
In a large mixing bowl, combine flour, baking powder, baking soda and salt. Using your fingertips, rub butter and shortening into dry ingredients until mixture looks like crumbs(Somewhere between pea size and cornmeal as long as its evenly distributed). (The faster the better, you don't want the fats to melt.) Make a well in the center and pour in the chilled buttermilk. Stir just until the dough comes together. The dough will be very sticky.
Turn dough onto Rice floured surface, dust top with flour carefully pat into a 1 to 1 1/2 inch thick round. Cut out biscuits with a 2-inch cutter, being sure to push straight down through the dough. Place biscuits on aluminum baking sheet so that they just touch. Don't use a non stick pan because it will cause the bottoms to burn. I used cooking spray to keep them from sticking.
This is important so they help each other rise. Don't squish them together but just have the edges touching. Reform scrap dough, working it as little as possible and continue cutting.
Bake until biscuits are tall and light gold on top, 15 to 20 minutes"