What is PDR ?
If you mean "PDF", then you can't using Reader. You need Acrobat for that.
Here's a workaround. Go to the page where you would like to have the bookmark. Create a sticky note (Comment>Sticky note), enter any text or no text and drag the sticky note to where you want the bookmark. When you want to return to the sticky note/bookmark, click on Comment to display the list of sticky note(s). Clicking in the sticky note/bookmark in the list will take you to that sticky note. Sticky notes may be deleted by clicking on its little triangle in the list of Comments and selecting Delete.
If all you want is to return to the point you left off when the document was closed go to Preferences>Documents and select "Restore last view settings when reopening documents".