Thank you for your post.
At this time, files exported from FileMaker Go can only be saved to the device. One possible option is to export and email the file to the hosted machine.
Or since the iOS device is connected to a database hosted by FileMaker Pro or Server, you could use a script to insert the PDF into a container field.
A script on the server could then move the file out of the container field into a location on the server.
Hmmm, wonder what would happen if we inserted a file into a container from the iOS client with external storage specified with storage specified for a location on the server?