I've tried using this software many times before and always gave up due to the browser issue... I saw where there was a new release:
so thought I'd give it a try, same browser issue, same error message pointing to xulrunner. I searched and searched and found that the issue (at least in Fedora 18) could be solved simply with one command:
ln -s /usr/lib64/libhunspell-1.3.so.0.0.0 /usr/lib64/libhunspell-1.2.so.0
In my instance apparently didn't have anything at all to do with xulrunner, nor did I need to do anything with permissions, etc.
I just unzipped rssowl, placed it in /opt/rssowl and issued the above ln command.
Again, this applies to rssowl-2.1.6
It's a nice touch the way the software opens a URL to help resolve a problem - but in this case the instructions tend to lead you down a rabbit hole. You might consider adding something about libhunspell - or better yet, fix the issue that requires libhunspell-1.2.so.0.
Here is the link to the post that helped me out btw... again, only needed to fix libhunspell, nothing else...
Does your OS have the same architecture as your download?
Yes, I downloaded rssowl-2.1.6.linux.x86_64.zip and I'm running Fedora 64.