I have joined while making the last stitch by inserting the hook into the bottom of the first stitch before doing the ch1 at the bottom of the last stitch, so: do any necessary yarn overs, insert hook in ch1 of previous stitch and bbring up a loop. Insert hook into bottom of first stitch, yo, pull that loop through the stitch and the first loop on the hook (ch1 made). Finish stitch as normal.

I find that doesn’t make for a seamless-looking join, but it’s ok for a lot of applications.

I’ve got a slew of new tutorials on this coming soon… the new ones show how to apply the foundation stitch technique to pretty much any pattern – any type of stitch, increases, decreases, holes, you name it. :-)