Have you ever heard of Google?
Since RHEL uses gnome by default, I did a simple google search for "
gnome keyboard layout hotkey". This turned up several pages that say you can configure one in the preferences of the gnome keyboard indicator applet.
(I don't use gnome though, so I can't confirm it personally.)
If you use another desktop, then you'll have to do some research on how they do it instead. In kde I know you can set it easily in the "keyboard shortcuts" configuration.