The FDA Center for Veterinary Medicine addresses this question in their VFD Q&A information:
Question: Established withdrawal times for the US are required to be listed on the VFD. In situations where the animals being treated are intended for an export market and the export market has a more stringent (longer) withdrawal time, how should that be handled on a VFD? Would writing an “export withdrawal time” in special instructions acceptable?
Answer: The VFD is required to be filled out with the information that is on the U.S. drug approval (21CFR 558.6(b)(2)). If it is necessary to include additional information specific to the care of the animals for export or other purposes, that information should be included on the VFD as special instructions.