Hello, I still haven't been able to use ribs. There seems to be a code problem with the Mac version. Perhaps it has to do with the "chmode" that Broks has pointed out in her post? Would appreciate some help! 

Thank you, R.

You do not need to +x the application bundle itself. You need to go inside the application bundle.

sudo chmod +x "/Applications/Ribs.app/Contents/MacOS/Ribs"

With that command it should work. Ribs.app is only a folder, the file I referred to in the command above is the actual "Unix executable file" and that file needs the x attribute in order to be recognized by Unix (and thus by MacOS) as an executable file.