K-L-N is used as a fertilizer suppliment and needs to be used with other fertilizers. You do not have the trace minerals needed to grow healthy orchids in K-L-N.
Yes, K-L-N is not a fertilizer, but rooting hormone. It can be used in small amounts along with your regular fertilizing regime. But if your orchids have large amounts of roots, it's likely not necessary. save it for when you are re-potting or trying to save a plant suffering from root loss.