A program executed by a computer for measuring an optimum feed amount to an RFID antenna from a print standby position of a printer which reads and writes data from/on an RFID tag by feeding a label or tag containing an RFID tag, and then prints on the label surface by feeding the label or tag in the reverse direction, having step of performing a read/write test to the RFID tag whenever the label or tag is fed by a fixed amount from a print standby position, and a step of outputting the result of the read/write test visibly performed in the steps.