Gluten-Free Flour Blend: To make flour blend, combine 2 cups rice flour, ⅔ cup potato starch, ⅓ cup tapioca flour and 1 teaspoon xanthan gum. Use appropriate amount for recipe; store remainder in container with tight-fitting lid. Stir before using.
Heat oven to 375°F. Combine flour blend, baking powder, baking soda, salt and xanthan gum in medium bowl. Set aside.
Combine butter, brown sugar and sugar in large bowl. Beat at medium speed, scraping bowl often, until creamy. Add eggs and continue beating, scraping bowl often, until well mixed.
Reduce speed to low. Beat, gradually adding flour mixture, until well mixed. Stir in chocolate chips.
Drop dough by rounded tablespoonfuls, 2 inches apart, onto ungreased cookie sheets. Bake for 9 to 12 minutes or until light golden brown (do not overbake). Let stand 1 to 2 minutes. Remove from cookie sheets.