^^^ Those engravers work well. Tag anything of value. I usually mark my tools and expensive items.
If you don't want it to show, do it under the battery. Put your name and phone number. Or, put your name and drivers license number. If found, police can easily run your DL# and return the radio.
If you want to do it on the front/side, just practice first so you get a feel how it works. There is usually and adjustment knob on the engraver that you'll need to fine tune.