A semicrystalline copolyester resin composition formed by twin screw extrusion of various ingredients includes copolyester resins, antiblock, slip and antifog additives. This semicrystalline copolyester resin can be extruded on to PET film or coextruded with PET resin to form clear PET films with antifog properties. These films with antifog properties are produced in a single step without the use of solvent and does not involve any secondary step for coating a separate antifog layer. This minimizes the cost and time required by a converter to make such clear antifog films. These films containing the heat seal copolyester resin can be heat sealed to clear APET trays. Contents within the trays, such as food, can be seen without fogging on the inside of the film that is used to seal the tray. The seals are strong and the peels are smooth giving a very good packaging performance.