OK, I think i’ve got a handle on it this time.
The thing is, I’m trying to do a non-standard cast-on. It’s a modified version of Elizabeth Zimmermans (EZs) “invisible cast on” for ribbing, Zimmerman, for some reason, knit several rows with her waste yarn before switching to the working yarn. Then she knit several rows of stockinette with the working yarn (how many depended on the weight of the yarn in question) and, while on a reverse side row, alternated between knitting the working stitches with the ‘live’ stitches revealed when she removed the waste yarn. She alternated between knitting and purling and set up her rib pattern that way.
I worked more carefully than I usually do with crochet cast ons. I made sure to pick up the stitches only through the back loop of the chain, and I marked the ‘end’ of the chain with a knot in the yarn. Then I oriented my knitting so that it would unravel in the direction of the knitting. The tail you see at the left of the picture is the end of the knitting round, so it’s the beginning of the chain (the side which wasn’t marked with the knot). Note the neat and even chain? That’s your check that you only caught the back loops of the stitches. It makes the chain much easier to remove… Trust me on this one.
Once you’ve got enougth knit, pull the crochet chain out s-l-o-w-l-y from the knotted end. As in, one stitch at a time. Pick up the freed stitch with the right needle, and slip (as if to knit) it onto the left needle. Then knit (or purl) it together with the stitch next to it. Since you’re pulling the stitches around towards the front of the needle, the ‘right’ side of the stitches will be on the inside of the closed tube you’re making, which is why you worked the opposing stitch from the one you would need in the set-up row. If you lifted the stitches to the back, there wouldn’t be any need to reverse stitches. It sounds easeir, but I found it to be counter-intuitive.
In the end, you have a more or less neat edge, with the ribbing pattern part of the cast on.