Using SharePoint to host PDF files, how to send for review for multiple files at one time

I am hosting large number of PDF files on a SharePoint document library.  I want to allow others to add comments to each file as needed.  How do we collaborate without having to click on each file, send for review, and add all of the recipients?  We have about 50 users and about 100 documents, so doing it manually is very cumbersome and hard to manage, i.e. add/remove reviewers.  Is there a way to allow the people with read/write to the document library be able to add comments to the PDF?

Thanks in advance,

Eli