Abstract: A perforating apparatus for use in the formation of shrink film packages is disclosed. The apparatus comprises a bottom seal tool with a plurality of peninsula regions forming a plurality of window areas. Each pair of window areas has a knife receiving area to receive a knife retaining block. The retaining block contains a perforation knife that extends beyond the surface of the sealing tool a sufficient distance to perforate the packages. At least one screw member extends through the peninsula, contacting the retaining block and securing the retaining block within the retaining channel. A change plate, having slots dimensioned and located to receive the knife blades is placed over the sealing tool surface. The packages are placed on the change plate and sealed by contacting the package with the upper platen. The upper platen is provided with a nonconductive material positioned to receive the knife blade.