Bulk adding comments to group of PDFs

I have a group of PDF's that are protected, but still allow commenting.

I want to add the same comment to the whole group, is this possible to do by an automated action? Possibly using the Action Wizard?

All I want is to be able to add a short text string that can be accessible somewhere in the document for metadata purposes. I cannot edit properties because of the security restriction. The comment can be the default size and font (currently 12 pt Helvetica), and ideally in one of the corners of the document.

I'm using Acrobat Pro XI.

Thanks!!