My .CHM file opens up in a ridiculously tiny window, and I
can't seem to change that from within Robohelp. I saw some
information on Rick Steve's site about customizing window sizes for
Webhelp and Flashhelp. I'm hoping there's a similar technique
available for HTML help.
In Project Manager, double click Windows and then the window
you use. There should be fields for setting the size. If not, check
that HTML is your primary output and then create a new window, then
you should see the fields.