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.