Preheat oven to 400°.
Combine baking mix and dill in a bowl; stir well. Cut in butter with a pastry blender or two knives until mixture resembles coarse meal. Add buttermilk and sour cream, stirring just until dry ingredients are moistened.
Turn dough out onto a lightly floured surface. Knead lightly 4 to 5 times. Roll dough to 1/2-inch thickness; cut with a 2 1/2-inch biscuit cutter. Place biscuits on a baking sheet lightly coated with cooking spray. Lightly coat tops with cooking spray.
Bake at 400° for 8 minutes or until lightly golden.