Not specifically for a K, but usual is 1 - 2 bar for tick-over, warm and 4 - 5 bar when driving, maybe a bit higher depending on Apollo tanks, oil grade, etc.
When I first got mine, my first drive, having just built it and got the plates that morning was with my brother in the car. We pulled up to some traffic lights about 5 miles from home and I glanced at the oil to see it at the first line above the red. I was 19yrs old and it was my first car, no experience of what it should be, apart from the stuff in the manual about getting 4 bar when running.
Panic sets in and I pull over to check level and for leaks... followed by a very steady drive home staring at the gauge (which of course was showing good pressure when running normally). I phoned Caterham only to be told 'that's is normal Sir, you muppet!' 😬
Phil Waters