If your skirt has side seams, pin and sew them now.
Kick pleat style 1
This is the easier style of kick pleat. I was planning to make a skirt with this style, but I couldn't find any fabric the colour I wanted, so I've done the technique in miniature for this tutorial.
First, pin and stitch the back seam, from the point marking the end of the zip down and around the kick pleat.
Clip the seam at the top of the pleat, and press the centre back seam open, with the pleat laying flat (there's no 'correct' side - one of my 50s skirt patterns has it laying to the left, another to the right).
Hand baste the pleat in place then, on the outside, stitch out from the centre seam along the basting line to secure.
Kick pleat style 2
This is the symmetrical kind of kick pleat often seen in vintage skirts.
Pin and stitch the back seam down to the kick pleat. If you didn't cut on the fold, sew the vertical of the kick pleat itself but not across the top of the pleat.
Mark a line from the centre back seam straight down to the hem, pin and then machine or hand baste.
Press open the centre back seam, opening the kick pleat and lining up the centre with the basted seam. Give it a good steam press to really set the creases.
Pin and hand baste across the top of the pleat. Then turn the skirt right side out and stitch the top of the pleat - I'm going to be covering mine up with a decorative tab, but if you're not, angling the stitch lines down slightly gives a nice effect.
Finally, remove the basting stitches.
Decorative tab detail
I love the look of a decorative tab detail on a kick pleat, and it's quite a straightforward thing to make so I thought I'd share instructions.
You may want to cut a template for your tab (I didn't). Start with a rectangle of fabric.
Stitch the long sides together, leaving a gap of about 1.5" in the centre.
Work the seam around so it's running down the centre - give it a light press to help it stay open if necessary. Then stitch a V-shape at either end of the tube.
Trim the ends close to the stitching and turn inside out by pulling through the gap in the seam. Use a point turner or another blunt-sharp object like a knitting needle or chopstick to push out the corners. Give the finished tab a good press.
Attach the tab to the skirt covering the stitching at the top of the kick pleat. I recommend using hand basting stitches to secure it as you sew the buttons on, as pinning through such a thickness tends to distort the fabric, which can result in skewed placement (trust me, I know).