Making pizza by ratio has definitely been a learning experience for  me.  I've made over 8 pizzas in the last 3 weeks (which is a lot for a  family of 3) and I have yet to find a 
"perfect" gluten free pizza  recipe.  That being said, I do have a go to recipe that is yummy and  easy and for now that's good enough!   This month's rally was hosted by 
Karen of Cooking Gluten Free.  Check out her blog for the complete list of links to the delicious gluten free pizza recipes created for this months rally.
Here are some things I learned:
Ruhlman's  Ratio- For Pizza Ruhlman's ratio is 5:3 of flour and liquid.  I tried  this and it was a dismal failure.  The dough was heavy and dense and  looked compressed and underbaked.  It felt like a rock in my stomach.   Gluten free flours need more liquid.  I figured out the ratio for my go  to crust, the one I 
posted here  and have been using ever since.  The ratio for this is 6:3:1  flour:liquid:egg  This ratio is close to Ruhlman's  but the addition of  an egg adds the right amount of moisture to create a nice firm crust  that you can pick up with your hands without being heavy and dense.  For  the flour I found that I like a crust with more starch than my usual  flour blend so I went with 50% high protein flour (brown rice, millet,  soy) and 50% starch (tapioca, potato, corn)
          
I  knew I had a crust I liked before I started the challenge, but I wanted  a go to crust that didn't use eggs.   I tried a few more flour:water  ratios including:
10:7 (dense and heavy)
19:16 (excellent)
8:7 (also excellent but I cheated and used an egg as part of the liquid)
1:1 (batter too thin)
Like I said, I learned a lot...there's nothing like a good failure to get the noggin thinking!
Even  though I tried several ratios, my main focus really was more on  technique.  I cooked my pizza at a hotter temperature (450 degrees  Fahrenheit), I let it rise for an hour before rolling it between 2  pieces of parchment paper, and I pre-baked it on the rack with a hot  pizza stone on the oven rack beneath it before adding the toppings.  All  of these things, together with the 19:16 ratio made for a great crust.
19:16  sounds like a strange ratio, but if you multiply it by 10 grams you'll  end up with an easy 18 inch pizza crust. Here's the Recipe:
Pizza Crust by Ratio
makes one 18 inch crust (or two 8 inch crusts)
190 grams gluten free flour
- 95  grams high protein flour (I used equal parts of millet, sorghum and soy  but play with this using flours you like or have on hand)
- 95 grams starch (I used 70 grams tapioca and 25 grams potato starch)
160 grams warm water 
1 Tablespoon yeast 
1 Tablespoon sugar
2 teaspoons olive oil
1 1/2  teaspoons xanthan gum
1/2 teaspoon salt
Mix water with yeast and sugar and let proof for about 10 minutes or until nice and foamy.   Combine  the remaining dry ingredients in a mixing bowl. Mix well. Add  the yeast  mixture and olive oil slowly to the dry ingredients and mix  on  low until the mixture is well incorporated. Increase the speed to  high  and continue to mix for 4 minutes.  The dough will be sticky.   Cover the dough with plastic wrap and let rise for about an hour or  until doubled.
After  an hour preheat the oven to 450 Degrees Fahrenheit and put a pizza  stone on the bottom rack of the oven.  Place dough on a piece of  parchment paper.  Spray a second piece of parchment paper and place it  on top of the dough.  Use a rolling pin and with light pressure roll the  dough to about an 1/8 inch thick (thicker if your prefer, but you'll  need to adjust the baking times).  Remove the top parchment and slide  the bottom parchment with the crust onto the oven rack.  Bake for 10-15  minutes or until the crust just begins to brown.  Remove crust from the  oven and top with your favorite toppings.  Return the pizza to the oven  for 10 more minutes or until the cheese is melted and crust is brown on  the edges.  Enjoy!