Here I'll show you how to knit encroachment, which is the opposite of a purl encroachment.
Here's what your work will look like. Its likely you've already completed a purl encroachment and this is just about the same. You will start with some of your stitches on the left-hand needle, and some of your stitches on the right-hand needle.
Use right-hand needle to lift the stitch from BELOW THE NEXT STITCH up ONTO the left hand-needle. Be careful not to let it get to close to the stitch that was already there.
Slip lifted stitch knit-wise from the left-hand needle to the right-hand needle.