You can register one custom paper size. This allows you to recall the settings quickly, which is convenient if you often use a certain type of paper that the machine does not detect automatically.
Press [Tray A].
Press [Paper Size].
Press [Program Custom Size].
Enter the horizontal size with the number keys, and then press [].
Enter the vertical size with the number keys, and then press [].
Press [Program].
Press [Exit].
Press [OK] twice.