Combine flour, baking powder, soda, salt, and sugar; cut in 2/3 cup margarine until mixture resembles coarse meal. Add buttermilk, stirring until dry ingredients are moistened. Turn dough out on a lightly floured surface; knead lightly 4 or 5 times.
Roll dough to 3/4 inch thickness; cut with a 2-3/4 inch biscuit cutter. Place biscuits on a lightly greased baking sheet; brush tops with melted margarine. Bake at 450 degrees for 15 minutes or until golden brown.
