Open the document to print.
Select [Print] on the [File] menu.
Select the printer you are using in the [Printer:] pop-up menu.
Select [Manage Custom Sizes...] in the [Paper Size:] pop-up menu.
Click [+], and then enter the name for the original paper size.
Specify the paper size by entering values in [Paper Size:] and [Non-Printable Area:] or [Printer Margins].
Click [OK].
Print the document using the print function in the document's native application.
Under some operating system versions, custom size paper cannot be registered unless "Any Printer" is specified as the target printer.
Due to calculation errors, the actual dimension of the custom size paper may not match the value entered by the user.