It's possible that it will show up on your output. The normal function of frequency dithering is to just spread the spectrum of the switching interference, which should work in the same way an FM modulator works. Ideally this only affects the output frequency content near the switching frequency.
But in a DCM converter, modulating frequency can also modulate the gain of the converter (depending on the control type), and it's not unthinkable that this could modulate the output at the dithering frequency.
What it comes down to is whether the bandwidth of the control loop is capable of rejecting the disturbances in switching frequency caused by the dithering. For most SMPS, rejecting frequencies up to 120Hz should be easy. If you do see low frequency ripple on the output, I would blame it on too slow of a control loop, rather than the dithering itself.
Using a pseudorandom profile would make the dithering more effective in terms of EMI, but for output ripple it still comes down to the bandwidth of the dithering vs the bandwidth of the controller.