PDF feedback

This allows a teacher to annotate and return PDF files that have been submitted by students. Teachers can add and position comments and draw lines, ovals, stamps, rectangles and highlights onto the student’s work, from within the browser. For Moodle 2.6 and above, I advise you use the standard functionality instead.
This plugin and the associated feedback plugin, do still, technically, work with Moodle 3.1, but they sit very awkwardly alongside the new grading layout. If you haven’t switched over yet, now is the time to do so.
This is part of the PDF annotation plugin for Moodle assignments.
Full instructions and information can be found in the submission part of this assignment plugin at:
https://moodle.org/plugins/view.php?plugin=assignsubmission_pdf
OR
https://github.com/davosmith/moodle-assignsubmission_pdf