There is no simple way to do this in KeyShot at the moment.
Take a brief look at
https://en.wikipedia.org/wiki/Retroreflector - the reason these materials look like they do is, that they reflect light straight back at the observer. In contrast a flat metal surface (or any other specular like reflection) reflects light at the angle of incidence - not back the way it came from.
Using an emissive will never give the correct behaviour since it does not reflect light in one direction, but emits it in all directions.
Here is a suggestion on how to reproduce this (note: I have not tested this myself).
Try to model (in your modelling software of choice) a plane with a
hexagonal pattern of recessed half-cubes (see second and third figure on the Wikipedia article). Then import into KeyShot and assign a metal material (e.g. with a pure white color) and add a small bright light source behind the observer (e.g. using a small bright HDRI editor pin og point light). This should give you the desired effect. Render out an animation or an XR to evaluate the result, since the viewer position is extremely important here. You will need at least 5 ray bounces (default is 6 so you should be fine).
You can find additional inspiration on surface geometries in the wikipedia article.
Note: you may be tempted to use a normal map for the recessed cube pattern, but that will not work.
Hope this helps.
Søren
