As the README.txt says
Administration > Structure > Content types (admin/structure/types)
For each content type it is possible to enable or disable the
PF link via the "Show printer-friendly version link"
checkbox. (default: enabled) It is also possible to
enable or disable the PF link in individual comments via the
"Show printer-friendly version link in individual comments"
checkbox. (default: disabled)
print_insert_link(), print_mail_insert_link(), print_pdf_insert_link()
The *_insert_link functions are available to content developers that
prefer to place the printer-friendly link in a custom location. It is
advisable to disable the regular Printer-friendly link so that it is
not shown in both locations.
Take a look at THEMEABLE FUNCTIONS
It is a best Practice to read modules README.txt.