Stumped-using the summarize feature in Preview with Automator

I'm scratching my head on this one. I am trying to create a workflow that basically does the following:

Find designated files
Open with Preview
Run the Summarize feature within Preview

The "running the summarize" feature is obviously not one of the pre-made actions within Automator, but I can't figure out how to do my own.

Any ideas or places I can go to read up more on tweaking automator?