HERE YOU HAVE A DETAILED TUTORIAL ON HOW TO CROCHET LACE FOR PLAIN NAPKINS.
When making the first knot, we leave a gap of only 1 cm from the corner. To hide a corner, we knit three slip stitches next to each other, then chain three, and finally a picot stitch, before inserting the needle into the corner to secure the picot stitch with a slip stitch.

In the same stitch as the last slipped stitch, chain 3 and repeat a Picot stitch, then return to the fabric and repeat the Picot stitch one more time. So you will get two more points.

Repeat the sequence of chain 3, 1 picot stitch, chain 3, 1 picot stitch, 1 space, and join the fabric with a slip stitch two more times (continue as indicated in the image), and so on until finished the circle, ending with a slip stitch at the beginning.