I've tried it on my PC by Exporting file as JPEG but can't find a way to include crop marks. Most obvious way is to add it to the page manually. Sorry I can be of help but am interested to know how.
There should be a sample script in the panel to add crop marks. This script will allow you to add manual marks around selected objects. If you are trying to export the entire page and add crops outside the page boundary, make sure you add a large enough bleed allowance in the document setup to hold them, and check the box to use document bleed settings during the export.