Blend dry ingredients in large mixing bowl. Cut in butter with a pastry blender, or use a food processor with dough blade. Add buttermilk. Divide dough into four pieces, roll each piece into a thin rectangle on a floured board or between two sheets of waxed paper. Prick all over with a fork, cut into desired size and place on cookie sheet. Bake at 375 until golden brown. Thickness will determine baking time. Check after 5 minutes.