Saving a permanently cropped copy of a file
A permanently cropped copy will show up cropped in any PDF viewer.
1. Tap the overflow button in the command bar.
2. Select Save A ...
3. Select permanently cropped copy

If the file has not yet been cropped, you will be asked to crop the document first.
See also
Cropping Pages
Saving a flattened copy of a file
Saving a reduced file size copy of a file
Saving a password protected copy of a file