Adding button to ticket page

What is the proper way to customize rt to add a button into a ticket so I
can perform an outside function?
What I want to do is to have a label printer print a address label from a
This would be done when the staff person is adding the ticket.
this should not be done for all tickets, and it only needs to be done on
I can use the ticket id to look up the correct information, I just don’t
know how to go about customizing for this…

Thanks in advance.