Print PDF with crop marks
If it’s a simple PDF document, you could possibly open it with Inkscape and then add crop marks with Extensions > Render > Printing Marks…. Or maybe Scribus, with Print… > Marks.
Very hacky but might help somebody in a tight corner.
If you have Adobe Acrobat Pro, this is easily done: File > Print > Advanced > Marks and Bleeds > Trim Marks
This may also be possible under Acrobat Reader, if someone would care to test it.