Looks like some have had success.
It may depend on the plating.
I had one jeweler completely fail trying to engrave a Tn gold clip. Ruined both clip and engraving bits.
Another jeweler refused to even try with his laser engraver.
24K would probably engrave. But, IMHO, why go to the trouble with an El Cheapo kit?
I ended up getting the barrel of the pen(s) laser engraved. Not same as clip but still beautiful and meaningful to the final recipient of the pen(s).
This is the first picture I have uploaded. Hopefully it will show up.
Here is a clip that Constant (lazerlinez.com) engraved for me.
It is on an Elegant Beauty from Aaron Lau. It did turn out better than the photo shows.
The flat surface of that pen clip makes it easier on an engraver, I'm sure.
Constant does a great job!
The pen is advertised as a Gold-Titanium plating. I believe the clip is Rhodium plated.
I bought it from laulauwood.com. It is also available at thegoldennib.com.
One of my friends uses the Cermark laser fluid with his laser engraver to egrave on the metal clips. There are two different solutions for the laser engraver to use, one for shiny polished surfaces and one for matte surfaces. And the fluids are not even close to being cheap. about $130 per 250gram bottle.