There are a number of threads in these forums about the best way to collect and merge PDF highlights and/or notes into a document that DT can read. I have just discovered an iOS app called LiquidText which appears to make it quite simple to do exactly that, and which produces a document which can then be imported into DT. It doesn’t have a desktop app, but since I prefer to annotate PDFs on my iPad, for me at least that’s not a dealbreaker (and there are a number of ways to get the final product into DT on the Mac, obviously). Does anyone else have any experience with it?
LiquidText is a solid app that I’ve used since it’s beta phase. It doesn’t get many feature updates anymore, but is well supported and reliable. Annotated PDFs can be exported to other apps that recognize the annotations. LT is particularly good with the Apple Pencil for annotation and handwritten notes, though the export is somewhat cumbersome for the handwritten annotations.
Alternatives are MarginNote Pro — recently upgraded to v3 — and more traditional annotation apps with annotation export such as Documents, iAnnotate, PDF Viewer.
A desktop-only app that is designed to work explicitly with DEVONthink for annotation export is Highlights.
You’ll find discussions here in the forum for all of these.
Thanks! So far, at least, I’m happy with LT. I looked at Highlights, but there were things that didn’t thrill me about it, and, as I said, I do most of my PDF work on my iPad, so LT works for me.