What would make it fail is the CHM would need to be on the user's PC and I doubt that would be the case. Also you would have to know where it is. I very much doubt there is any way to embed a CHM in the PDF.
With another poster in another thread, I am try to establish how lately posts are ending up with the body of the post also being the title. Grateful if you can throw any light on that.
See www.grainge.org for RoboHelp and Authoring tips