I am having a problem with Okular when dealing with annotation functionality. I am able to do annotation (write note, etc..) on PDF document but then once it is saved and reopened using Evince or Okular itself, it will not appear as the annotated version of it (The note written does not appear). Is it a bug in the Okular application or have I overlooked something?
See this question which inadvertently answers your question.
Okular doesn't store the annotations on the document itself, rather it stores them in an XML file, in a location specified below. Unless the format in the XML is recognised by another reader - Evince - then you are out of luck.
In your case, if Okular itself cannot find the annotations, make sure you have the directory (~/.kde/share/apps/okular/docdata).
Note that Okular isn't itself a PDF reader, rather it uses 'backends' - see this link