Obviously, it will only work on instruments which have different samples assigned to each note (or most of notes to some degree). If the instrument is based on a single sample, stretched all over the note range, it will produce no audible results.
Besides 'faking round robin', it can also fake classic stereo effect, where you record two takes of the same phrase and then pan them in stereo. There are two controls. Round robin range is, how far from the original note can the machine look for substitutions. When range is set to zero, the effect if off. Stereo spread activates stereo effect. It only works when round robin is active. It simply triggers another random note and then positions both notes in stereo field according to spread value. In some cases it can produce a flanging effect.
I don't know, how to automatically detect instrument's note range in Kontakt, so it has to be set manually, by editing values in the script. Else some notes may wander off instrument range and produce no sound in effect.
Here's how it works, applied to one of Kontakt's factory e-pianos.
The effect can be subtle or weird, depending on instrument and settings. If you'd like to go weird way, try it on a choir library and push it to the limit.
The script is using classic algorithm to generate random numbers. It will restart the generator on transport start (whenever you press play in DAW), so if you use it in a project, it will always render the same result.
You can download the script here. It will work Kontakt 4.2 or newer. Have fun with it.