Maryse,
I don't think the size of the file should be an issue, even
when it's 13 MB. I'm sure that other people have been distributing
much larger files than this without problem for many years.
You say "
some people cannot view help", which suggests that other
users are not encountering the problem. In other words, the methods
that your software developers have used to connect the help file to
the application do work properly, if not for all users.
When users who cannot view the help press F1, does nothing
happen, or does the help viewer open but with an error message in
the right-hand topic pane? Is the large file the only one that is
affected by this issue, or are all the other help files in the
collection also affected?
If it's of any interest to you, you don't need to compile a
PDF file into a help file in order to display the contents of the
PDF in the help file. Microsoft has published the following script
for linking to an external file from a help topic:
http://msdn2.microsoft.com/en-us/library/ms644690.aspx
Pete