Knitted cast-on in purl?

I’m knitting a Picovoli (two years late, I know!) and have just gotten to the armholes. The pattern suggests doing the “knitted cast-on in purl” for the underarms to make a snug edge. I can’t figure out what this is - does anyone know?

I did a knitted cast-on, which was pretty loose, so I want to take it out and try again. I tried purling and guessing how to slip the stitch back onto the needle, but it didn’t work – my working yarn ended up staying at the beginning of the cast-on stitches.

Hi RuthK…would this help?

Thanks, Susan, but I don’t think I can use that because I’m casting on in the middle of the row. I can’t do a long-tail cast-on. I appreciate it, though!

hm…In the following this lady had the same problem and she tells how she resolved it…halfway down again re the 'knitting yet another felted bag":

Hmm…that wouldn’t suit middle of the row either would it…hmmmm

How would this backwards cast on go…half way down page…this is the only technique I’ve seen that sounds close that can be done in the middle of a row:

A purled caston is like the knitted CO except you do the stitches purlwise. I’ve done it, both as starting CO and for armholes. It looks like the crocheted CO, a nice chained edge. It’s a little awkward at first, but so is any new thing. Here’s a how to -

Thank you! I’m set to go now!