COMBINE rice flour, potato starch, tapioca flour and salt in medium bowl. Cut in butter with pastry blender or two knives until mixture is crumbly. Form well in center. Add egg and vinegar; stir gently with a fork until just blended. Sprinkle with water; blend together with a fork and clean hands until mixture just holds together and forms a ball. (Be careful not to add too much water as dough will be hard to roll.)
SHAPE dough into ball and divide in half. Cover one half with plastic wrap; set aside. Place remaining half on lightly floured (use rice flour) sheet of wax paper. Top with additional piece of wax paper. Roll out dough to 1/8-inch thickness. Remove top sheet of wax paper and invert dough into 9-inch deep-dish (4-cup volume) pie plate. Slowly peel away wax paper. Trim excess crust. Turn edge under; crimp as desired. Repeat with remaining half.
• This dough is easiest to roll and work with when used soon after preparing it.
• This gluten-free pie crust is great with LIBBY'S® Famous or Lighter LIBBY'S® Pumpkin Pie filling found on VeryBestBaking.com. No need to prebake the crust. Just substitute this crust for the deep-dish pie shell called for in the recipe. Follow the temperatures and bake times stated in the recipe.
• If a prebaked crust in needed for your recipe, preheat oven to 400° F. Bake for 15 to 18 minutes or until crust is set and pale gold. Cool completely on wire rack.