In RB quickest easiest way is to use the AUX Send and put the FX in the the AUX FX area (upper right of mixer screen).
There are 8 AUX busses available.
To send the track to a given buss, there is a dial on the mixer for each track.
If it is a MIDI track the dials are for Reverb, etc., but if it is an Audio track the same dials are Auxiliary Send dials.

The other option is to use the Subgroups in the bottom right corner (15 of these available) but this can be more complicated depending on the sound card configuration.
I happen to use that area for multiple outputs on my sound card sometimes as it can be used for either that or combining SubGroups., so AUX is easiest and was designed for this task.




I do not work here, but the benefits are still awesome
Make your sound your own!