This is basically a tuck edge. This can be done at the start of your knitting and as well as after the piece is finished. In either case, the actual procedure remains the same.
In the sample shown below, there are eight stitches between every tuck and the tuck stitch is done for four consecutive rows. You can either use a card, an electronic pattern or simply pull out the needle to select the specific needle to be tucked on a Japanese machine or put a pusher under the needle to be tucked on a Passap. Then set your machine to tuck while you knit four rows. The act of pulling up on the stitch for four rows in and of itself will cause the scalloped shell edging shown below.