PDF (Printable Document Format) is an open standard for document exchange created by Adobe Systems in 1993. If you need documentation to look the same way in every platform, you can use PDF format to create printable manuals. PDF files created with the Dr.Explain contain Topic of Contents (TOC), bookmarks, links, and graphics.
There are several ways to publish your help project to PDF:
click on the application toolbar;
go to the Options menu and click the Export to PDF menu option;
use the Alt+Shift+D keyboard shortcut.
Once you select this option, the following dialog appears:
This check box does not appear until you publish your first PDF file. If you select it, you will skip the Save As dialog next time you generate your PDF file.
on the application toolbar;
Click this button to display the 
Click this button to start the publishing process.
Click this button to close the Export to PDF file dialog.