I would use 75 ohm cable, since reflection from the other end is possibly worse, as Al stated, but also because output RCA connector is not likely 75 ohm anyway.
I would use very short cable - as short as possible. Wire becomes transmission line when propagation time is longer than 1/8 of transition time. Assuming typical 25ns output transitions cable should be limited to propagation time of about 3ns, equivalent to about 2 feet (5ns/m). Since internal connections on both sides (including PCB traces) count I would limit it further to 1foot max. Otherwise I would use 1.5-2 m cable to ensure that reflections from the other end miss originating transition.
I would use very short cable - as short as possible. Wire becomes transmission line when propagation time is longer than 1/8 of transition time. Assuming typical 25ns output transitions cable should be limited to propagation time of about 3ns, equivalent to about 2 feet (5ns/m). Since internal connections on both sides (including PCB traces) count I would limit it further to 1foot max. Otherwise I would use 1.5-2 m cable to ensure that reflections from the other end miss originating transition.