Xanthan Gum Additions:
When mixing gluten free flours we normally need to add xanthan gum to recipes. When using a purchased flour blend mix, it may have xanthan gum or guar gum added, if this is the case you will not need to add xanthan gum. I always bake with multiple flours so here is how I add xanthan gum:
Cake: 1/4 tsp xanthan per cup of flour called for in the recipe
Bread: 1 tsp xanthan gum per cup of flour called for in the recipe, sometimes you only need 3/4 tsp per cup of flour. You will be able to tell by the texture, start small and increase if need be. Although I will say, I always use 1 tsp per cup of flour in my breads.
Pizza Crust: 2 tsp. per 1 cup of flour
Cookies: 1/4 to 1/2 tsp per cup of flour
Happy Baking! :)