Melt butter and marshmallows; stir until smooth. In a large bowl, mix rice cereal, candy corn and miniature chips together. To marshmallow mixture, blend in 2 drops yellow food coloring and 1 drop red food coloring, adding more coloring if necessary to reach desired shade. Add marshmallow mixture to cereal mixture; stir quickly to combine. Spread on a large buttered pan; press with buttered hands. While warm, press on candy pumpkins spaced 1 to 1/2-2 inches apart. Refrigerate and cut into squares.