Lightly grease 8 inch square pan. In top of double boiler, combine caramels and milk. Cook over hot water until caramels are melted, stirring occasionally. Remove from heat. Add margarine; mix well. Stir in powdered sugar; beat by h and until smooth. Stir in peanuts. With buttered fingers, press mixture into greased pan. Refrigerate 1 to 2 hours or until firm; cut into bars. Store in refrigerator. Makes 18 bars.