To set up a custom paper size, open the Control Panel and then open Printers. Under the File menu, choose Create a New Form or Server Properties. Select the Create a New Form check box and define the form’s dimensions. Click on Save Form or OK.
Once the form is defined, you will be able to select the custom size in your printer driver. Right click on your printer driver and select Properties. In the driver, go to Paper Size, select your custom size from the menu and apply the changes.
When you ask the program to print your checks, click on the Properties button in your printer driver; in Paper Size choose the custom size, click OK and then OK to print.