The finished look for the collar

 Step 1. The drawstring casing is ¾" wide, finished (I started with 1¼" wide). Staystitched at ¼" along both long sides and turned to the wrong side. I made the casing 25" long...but this would really depend on the size jacket you were making. You want the drawstring casing to stop about 3"- 4" back from the vertical front fold of the band on the underside of the collar when folded into the final position...so from the top side of the collar you only see 2 rows of stitching...faintly.

I turned the two short front sections of the drawstring casing back ¼" and stitched them before applying the casing to the underside of the garment collar.

The garment was totally finished first. I wanted the stitching to go through both layers of the collar...if the casing was only attached to the underside of the collar...it would not gather the top collar correctly and just 'bunch' up in clumps.

I put 3/16" Steam-a-Seam along the long ¼" turn back edges of the casing as close to the edge fold as possible. The placement for the drawstring casing is 1½" above the neckline where the collar joins the body of the garment at the center back and parallel to the top edge fold of the collar band. This is placement for the long bottom edge of the casing. Make sure the casing is parallel to the top fold of the collar and centered so both ends are the same distance back from the front band fold.

Stitch the upper and lower long edges of the drawstring casing. Tying off at all four corners on the under side of the collar so no back stitching is visible on the top collar. It's all in the details!

Step 2. The long drawstring is ½" wide finished and 45" long....I did my drawstring on the straight of the grain (a. didn't have enough fabric for a bias cord, b. I was using 45" fabric...so I have the selvage at both ends of the drawstring and knotted the ends after the drawstring was slipped through the casing, hiding the selvage, c. you only see about 6"- 8" of the drawstring after it is put through the casing.)

The collar is pulled it up just slightly to make the it stand on it's own. That's it, you're finished.