Why do you need to print from FileMaker? Surely it makes better sense to open the PDF in its native software and print from there. Internally. FM can generate PDF files (reports, etc), it can store them in container fields, it can export them from there, but it can't natively print them, except by calling an external process (Perform Applescript, for example, or install an appropriate plugin).
I had a related question. I have users who are on iPads using FMgo, they have access to forms which are saved as a pdf in a container field. Currently the user has the ability to export the file to a temporary file and then print the file from there on the iPad. Is there anyway to automate this so they can print in one step instead of multiple?