Here it is the screenshot, clicking on the ballot there appears the annotation. I already tried okular but I'm not able to reach the same result (actually to save annotation I have to export the pdf as Document Archive, which makes it unreadable for every other pdf reader)
I opened it with Document Viewer
// UTF-8 sure, but I would lose the annotations, I don't get what you mean
– Vittorio Apicella Nov 08 '15 at 16:21