Drawing from distant memory here. I believe RoboHelp expects Word DOC files. It saves as .RTF if you create WinHelp files, but I believe the main file type is .DOC. I'm unaware of any way to force it to only work with RTF.
Then again, I never ever claim to know it all about any given subject. So perhaps someone has a clue on how it might be accomplished.
Out of curiosity, if you want CHM files and CHM files are HTML based, why the insistence on RTF as your source? Why not convert to RoboHelp HTML and work with HTML content?
Excellent question. My reason is that we were told to do so. Personally, I'd be fine with the .DOC and .RTF happily coexisting inside of RoboHelp since I can tell by timestamps they are in sync when I make a change - both could be put into source control.
I was told we should be able to ditch the .DOC files that were edited for WinHelp (which in turn edited the .RTF files) and continue with only the .RTF files.
The person who maintains the help content has been using Word for years and we've been told that the RTF files should be what will be edited and checked in to source control.