I've done k1 below but never K4B. I would assume it would be the same way as K1B except picking up the forth stitches below instead of one. I've looked around the web to find some answer just to make sure my assumption is right. I came across this pattern call "Tuck Stitch" which involves K4B.
Here is a link to a video that show how to do K 4 below.
My pattern sets a 4 row eyelet pattern on the raglan. The 1st row decreases 1 stitch at each end. 2nd and 4th rows are purl. The 3rd row, is as follows: