but if you really don't want those RF currents (perhaps your cable just happens to be the right length to form a monopole antenna to radiate interference) you can add a ferrite bead around the cable. this causes common mode currents to see a higher impedance at high frequencies, and this reduces the current.
in my experience with complex interconnected systems, this can turn into a game of whack-a-mole as the RF return current will find a path back (oh yes it will!) using a different route--and it may be a less desirable one!