Gluten Free Thin Crust Pizza - Tips and Explanation?
Traditional yeast based pizza crust is essentially a yeast raised flat bread.  Its structure and chewiness is the result of gluten development from the wheat proteins&mdash;the very aspect you are trying to avoid.

The recipe that you have has three basic components:


Yeast, to develop some of the yeasty flavors
Starch which will form the matrix of the crust (tapioca, brown rice flour)
Gums or thickeners to give it enough structure and strength to hold together cohesively (gelatin, xantham gum)


There is nothing in the formula you have provided which should be scraping the roof of your mouth like the infamous breakfast cereal.  The closest thing to a suspect is the rice flour, which if it is brown, is milled from the whole rice grain, including the outer hull or husk.  That might be what you are finding texturally unpleasant.  You might try another brand of rice flour, or using white rice flour in its stead.

It may also be from over baking--if you are only getting the abrasive texture from the edges where it is most cooked, you know that you should simply cook it less.