add information to superbill template

There seems to be a default superbill.pdf template used by the system - how can I add information to this template? I need to print our superbills and forward them to my RCM company, and some informations are missing in the default superbill.pdf. There are hundreds templates callewd "superbill.pdf" in the charm library, however, i don't know which of those is used by default.

Thank you!