This video shows how to work the Tubular Bind off. I'm working on the Zahavi Sweater by Emily Greene and distributed by Brooklyn Tweed. The instructions given in the pattern for working Kitchener Stitch Tubular Bind off follows:

"Kitchener Stitch is used to sew live stitches together in a way that mimics a row of knitting. Pieces to be joined are live on needles, with RSs facing out and both needle tips pointing to the right. Use a length of yarn approximately 4 times the length of the finished seam, attached to the R edge of the fabric on the Back Needle (use the yarn the piece was knitted with, or attach a new length of yarn). Thread the yarn onto a blunt tapestry needle and follow the instructions below, working from right to left (note that you will work into each stitch twice):

Step 1: Insert tapestry needle into first stitch on Front Needle as if to purl; pull yarn through, but do not slip this stitch from needle.

Step 2: Insert tapestry needle into first stitch on Back Needle as if to knit; pull yarn through, but do not slip this stitch from needle.

Step 3: Insert tapestry needle into first stitch on Front Needle as if to knit, slipping this stitch off the needle. Insert tapestry needle into next stitch on Front Needle as if to purl and pull yarn through this stitch, tugging it gently.

Step 4: Insert tapestry needle into first stitch on Back Needle as if to purl, slipping this stitch off the needle. Insert tapestry needle into next stitch on Back Needle as if to knit and pull yarn through this stitch, tugging it gently.

Repeat steps 3 and 4 until a single stitch remains on each needle, adjusting the tension of the sewing yarn every few stitches so that it mimics the tension of the knitting. To finish, insert tapestry needle into final stitch on Front Needle as if to knit, slipping it off of needle. Now, insert tapestry needle into final stitch on Back Needle as if to purl, slipping it off of needle. Pull the yarn through and fasten off gently so as not to distort the stitches." © Brooklyn Tweed 2020