A K-ration is a kind of comestible. K-rations are not normally generated, but soldiers (of all ranks) have a 1/3 chance of starting with one, so they are commonly found while assaulting the castle and Fort Ludios. K-rations and C-rations are effectively identical, except that K-rations have a higher nutrition value.
K-rations can be eaten in one move, making them valuable for nutritional purposes when you are in desperate situations. In fact, they have the highest nutritional value of any one turn comestible and are therefore the favored form of nutrition for the Astral Plane (and facing Famine).
K-rations are suitable for vegans.