Instructions from 1950’s Semco Crochet booklet
KNOT STITCH (k st): Having one loop on the needle, draw it out to the length of 3 ch,
thread over the needle and draw through, making an ordinary chain stitch, drawn out to three times its normal length
Then put the needle under that one of the 3 threads of the long loop which seems to lie by itself, draw the thread through and make a single stitch. This is the knot stitch.
It is usually worked by making two, then fastening to the previous row by a single stitch unless the row was knot stitch, in which case work one single stitch each side of the single stitch between the two long loops or knot stitches.
© Sarah Bradberry