My understanding is that RCAs only have the one insurance option. United Healthcare thing. Like all insurance stuff, it is confusing to me, but it is the main reason I took the job (as a retiree)-- just to have something in case of "the big one". It has a high deductible, but offers office visits with a co-pay, and seems to cover some other junk. I will say the dental coverage is nice. Two cleanings/visits a year for free.
Luckily we are basically healthy, and don't go to doctors much, knock wood.