The first step of printing should be to visit File > Page Setup (Command+Shift+P) if you need any special settings or to double-check the settings you have now.
To print to a non-standard-sized paper:
- File > Page Setup > Paper size.
- Specify your special paper size.
- Select the printer you are using.
While PDFpen can handle documents with variable page sizes within the document, such pages should be printed separately with the appropriate Page Setup for each.