Preheat oven to 375°.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and the next 5 ingredients (flour through salt) in a bowl; cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Add cranberries, tossing to coat.
Combine buttermilk, rind, and egg; add to flour mixture, stirring just until moist (dough will be sticky).
Turn dough out onto a lightly floured surface, and knead lightly 5 times with floured hands. Pat dough into a 7-inch circle on a baking sheet coated with cooking spray. Cut the dough into 10 wedges, cutting into but not completely through dough. Bake at 375° for 30 minutes or until golden. Sift powdered sugar over scones; serve warm.