Matching regexps from a file?

I'm on umpteen mailing lists, which I filter to a file "mysave", using
this recipe:

:0:
* (\
   
^Resent-Sender:(_dot_)*procmail-request(_at_)Informatik\(_dot_)RWTH-Aachen\(_dot_)DE|\
   ^List-Server:(_dot_)*info(_at_)fringeware\(_dot_)com|\
   ^Sender:.*Spam Prevention Discussion List|\
         [etc.]
  )
mysave

If I keep adding new lists, though, I suppose it'll eventually reach the
point where it's too long a "line" for Procmail to handle.  So if I had
a separate file named "keyfile", where each line is a regexp
corresponding to a mailing list:

^Resent-Sender:(_dot_)*procmail-request(_at_)Informatik\(_dot_)RWTH-Aachen\(_dot_)DE
^List-Server:(_dot_)*info(_at_)fringeware\(_dot_)com
^Sender:.*Spam Prevention Discussion List
    [etc.]

How would I write a condition line that would make Procmail check the
header lines of incoming mail to see if any of them matched any of the
regexps in the "keyfile" file?