SIGN PDF WITHIN SHAREPOINT ONLINE

Have a PDF form that has the flags to digitally sign. This is an official form.  The document is loaded to SPOL.  When I open the PDF and from the browser, the flags disappear, consequently, document cannot be signed.  Want the flags to appear and sign just as if I was opening the doc on my desktop.  We want to upload and sign all in one repository on SharePoint.  
Any suggestions? 

Assistance will greatly be appreciated.

V/R

chudson002