First cut out the shirt front, placket and placket interfacing.
Apply interfacing to the wrong side of the placket.
Next, cut a small square of interfacing and attach to the very button of the placket opening in the shirt. Do this on the wrong side of the shirt front. This is not in the pattern directions, but I felt it made that area just a bit more stable and I was happy with the end result.
Okay...now you have the interfacing on both pieces....
Sew gathering stitches along both sides of the placket opening. I like to sew 2 rows.
Adjust gathers to fit placket piece. Now here is where I did something different. I cut a diagonal slit at the bottom of the placket opening before sewing the placket. The cut I made was the same width as the seam allowance I was sewing with. Approx. 3/8.
I'm going to pin....right sides together...one side of the placket to one side of the shirt. I will sew from the top of the placket opening and STOP when I get to the diagonal cut.
All pinned and ready to sew....
See a close-up of the cut. This is where you will stop sewing on both long sides of the placket. Sorry for some reason I didn't get a picture of the actual sewing along both sides of the placket.
After both long sides are sewn, pinch the short side--bottom edge of the placket together.
You will sew along that edge.
This is what the back will look like.
Finish the edges with a serger or sewing machine set on a zig-zag stitch.
Take your shirt front to the ironing board and press the placket. Iron the side seams and the bottom short seam of the placket all in.
After pressing, carefully topstich along all three sides of the placket.
Your competed placket.
This is just what worked for me and I thought I'd share and maybe help someone out.....