If you're trying to make something gluten-free by subbing rice flour, you'll need to add other ingredients. This combination works very well for me for most baked goods:
1 cup any gluten-free flour (or rice flour)
1 cup sweet rice flour
2-4 Tbls tapioca flour

Gluten-free Girl also has some good information on her blog. She has very good advice on how to make something gluten-free and still whole grain. (Look for it near the middle of this page in the link.)
http://glutenfreegirl.com/gluten-free-whole-grain-muffins/

According to the Joy of Baking, you can substitute rice flour for most of the quantity of AP flour in a baking recipe, but not all of it. See here for more info: http://www.joyofbaking.com/IngredientSubstitution.html