For an X we would carry a "Linoleum knife", hooked knife with yellow handle, but at the end of the blade it had a Hardened edge ( i believe it wasmore for scoring tile).
We also used the ole' lead plug and tack trick which required minimum drilling with a hand "star" drill into concrete (Hilti hammer drill if we were prepared)
I use a full size (7-1/4") Skill brand skill saw. I usually cut an "x" or arrowhead for corners or witness marks if needed in concrete, and witness them with a monument with my license number, and show it on my plat.
Thankfully, the states I am licensed in allow this, or allow us to set witness monuments.
I picked up the saw in a kit at CPO Outlets, it was a heck of a deal, and picked up an extra battery, and an extra charger for a total of three batteries and two chargers. I put a diamond blade in it, and it works great for the few times a year when I need it.
I'll either use a cordless 18V drill with a masonry bit and set the nail in that hole but it's not countersunk and may chip off with a snowplow, or I'll use a small plug in power inverter in the truck to drive a standard 110V Dremel and cut crosses using standard Dremel cut off blades. The Dremel will cut nice small and deep crosses and won;t overdraw a smaller inverter.
