You can load PDFs directly in and then customers can either leave a regular comment or better yet an "inline comment". When they have the document preview open (renders the PDF in a preview window) they can double click on any part of it to make a comment. For example if I had a 30 page PDF loaded someone could go to page 3 at the second paragraph and double click to add a comment like "This needs to account for XYZ" while they are looking at it in the preview window. All of this is Jive out of the box to my knowledge (no plug-ins needed). You may have to tweak user permissions to allow them to comment on documents if they don't have those rights already.
We have all of our documents (mostly PDF) loaded in our Jive external Support Community, and have seen a few comments but not a lot. We have only been live for two months though. We have not directly enlisted our customers to review our documentation. Our hope is that it will happen naturally as our support team points customers to specific documents daily. If you just want your customers to review documents without them having a current need to look at them for their own benifit you may have to figure out a way to motivate them with a contest, some publicity, or some sort of gamification.
Thanks, Matt. This feature is very useful - I wasn't aware of it at all. I tried it out in our sandbox (we're not live yet), and it worked great. You can enter in-line comments, and then these comments are shown right under the doc preview and you can click to go directly to each comment within the doc.
Thanks for enlightening me!