How do you create a "flat" PDF file in Acrobat X for Mac?

I'm using Adobe Acrobat X on a Mac.

I have made some edits to a PDF by adding text  and lines.  I want to save the file as a flat file so that no one can delete/edit my edits.  In Windows, you can just print the PDF to PDF.  When I try to do this on a Mac, it says "Saving a PDF file when printing is not supported. Instead, choose File > Save."

When I just choose File > Save, it just saves the PDF in the same format that allows those edits to be changed.