This is a very common problem. I remember when I tried Suse 9.1, and did everything to get a matrix screensaver. It was then when I decided I will give a try to xscreensaver and dumped kscreensaver for it. (Later dumped Suse in favour of Gentoo.
Anyway, search for anyting named matrix (should be either glmatrix or xmatrix) using command:
There should be a binary named, for example, glmatrix. On my Suse 9.3 sysem, it is located in /usr/lib/xscreensaver/glmatrix
Correspondingly, there is a .desktop file which KDE reads, and which points to this file:
This is the file that is read and listed by kscreensaver. Ofcourse I am Suse which is particularly known to reconfigure everything
, and it should be easier to find the glmatrix.desktop on FC (though I dont know)
If you dont find anything, you can just go the directory which is checked (in my case, /opt/kde3/share/applnk/System/ScreenSavers/), and create a desktop entry pointing to the /usr/lib/xscreensaver/glmatrix
Hope this helps. A guy working on FC will be of more help.