I have found this in one of the sites
To test PrintMulti, we recommend installing a local printer, which prints to a single file (see the example)
The following conditions must also be met to use PrintMulti:
1. The PrintProcessor ”PrintMulti“ must be assigned to the printer in the advanced options dialog.
2. The relevant configuration file must contain a section for the printer, the Entry ”Active“ must be set to ”1“ and
at least one action has to be defined.
You can refer this detailed doc on how to configure PrintMulti