It's easy to add picots (little side loops) to square knots. Just make ordinary square knots (worked flat) a distance apart from one another, then slide them up the center strands.
If you want a series of picots it is usually easiest if you tie one knot then slide it up instead of tying a long series and trying to slide all of them. To keep your picots even you'll need to measure the distance between square knots.
To form a picot on only one side of a row of square knots you'll want to tie them close together and wrap the one picot strand around a pin that is placed to the side of your work on your cork/pinnable surface.