Custom Printing
4.If the Paper Size setting you selected is larger than the maximum size that can be printed on your printer, you see the following dialog box:
In the Output Paper list, select the actual size of the paper loaded in the printer and click OK. This automatically turns on proportional printing and sets the correct reduction percentage so the document fits into the printable area on the output paper you select.
The selected Paper Size, reduction percentage, and
Output Paper settings now appear on the printer graphic.
If you want to adjust the proportions or sizes, go to step 5.
If you’re ready to print, go to step 7.
Paper Size setting
reduction percentage 
Output Paper setting 