With the Set printer workflow component you can tell InterFormNG2, which system printer, that you are going to use.
The Set printer workflow component has a single parameter:
Printer name
The name of the printer, that you are going to use. If you click either the line or the arrow, then you can select the printer from the list of installed printers.
You can also click the rightmost icon to setup an XPath expression to select the printer dynamically.