Does your pattern explain what they want anywhere? Read everything and maybe it is there in some weird place.
K1b can mean 2 things that I know of. One is knit 1 below, which means into the middle of the stitch below the needle, not where you usually knit. This seems unlikely to me in this case, but it could be.
The other is knit one behind. Which means to knit into the stitch loop on the needle but behind the left needle instead of in front. You move the right needle right to left into the stitch, sort of like you were purling, but behind the needle. Go into the stitch, yarn around and pull up a stitch loop but don't take it off the left needle. Then take the working yarn to the front between the two needle tips (that makes the yarn over when you do the next step) then knit again into the leg behind the needle and take the stitch off the left needle. This makes 3 stitches out of one and causes an X to be formed at the base of the three new loops.
Does that make sense in your context? If it is knit one below knit into the middle of the stitch below the needle, but don't take the stitch off the left needle, make the yarn over the same way as above and then repeat the knit into the middle of the stitch below and now take the stitch on the needle off. Could be.
You might try each (unless you find the instructions on the pattern) on a swatch and see if either is anything like what you are going for. Another thing... maybe you could go to their Web page if they have one (and who doesn't these days) and see if it tells anywhere or send them an e-mail and ask.