Hi Petra,
Sorry for the late reply.
Unfortunately, currently, we don’t have a tutorial for that, however, let me try to help you. Could you please let me know which print button/option are you trying it with? E.g. is it from the single product edit page, or from the admin “Products” list’s “Bulk actions”? If it’s from the single product edit page – there are two buttons there – one for direct printing, and another one for the PDF – which one are you trying it with?
P.S. If you wish, I can log in to your site to check what’s going on (my email is [email protected]).