<<Disclaimer: Verify this information before applying it to your situation.>> Scott, The proportions of Betty Hagman's GF flour mixture is 2 parts white rice flour, 2/3 parts potato starch flour, and 1/3 part tapioca starch. I usually up the measurements by a factor of three so that it comes outs to 6 cups, 2 cups and 1 cup respectively. I put this in a flour canister, mix it well and use as needed. Ellen Eagan eagan@ pangloss.ucsf.edu