Creating and Saving Custom Sizes for Macintosh
1. In the application, click File > Print.
2. Click Paper Size, then select Manage Custom Sizes.
3. To add a new size, in the Manage Paper Sizes window, click the plus sign ( +).
4. Double-click Untitled, then type a name for the new custom size.
5. Enter the height and width of the new custom size.
6. Click the arrow for the Non-Printable Area field, then select the printer from the list. Or, for User Defined margins, set the top, bottom, right, and left margins.
7. To save the settings, click OK.