This started as a requested item for the 2007 IDPA "postal" match, but I'll leave it in as it may be interesting for large matches as well.

Enable it in Program Preferences.

 

Once that's enabled, you can select for a particular match.

 

Then there is a new entry field when you register shooters.  It will default to the shooter's state (as it exists in the shooters database), but you can type something else (such as a club name) if you prefer.

 

At this point, only web results (NOT print/PDF) will show this information.  Check the box in the Web Page Wizard.

 

Et voilà