annotating ppt with pen during presentation then saving using surface pro 3

[WPCentral Question]

Hey - am running PPT presentations for a class I am teaching and annotating the slides with the pen on my surface pro 3. At the end of class I can save all of the annotations to the ppt - but if I convert that file to a PDF for the students, none of the pen annotations are saved. I don't want to post the complete PPT because of all of the information located in the note sections that I use for exam questions. Any ideas?