With chalk I marked this spot 1/2" in from the side seam(where the fins are inserted) and then the 10". This left about a 1" seam allowance from the top edge, which I continued to mark around to my other side seam.
Start the tape just beyond your X mark and pin it just above your top chalk line.
Here you can see the entire top edge of the glove pinned. It is important that you pin this as it lays flat on the table. As you are sewing it the Gauntlet fabric will want to stretch on you, which you want the twill tape to prevent.
Stitch this about 1/8" from the top edge of the tape.
Press again rolling the tape to the inside of the gauntlet. Pin and sew 3/8" from the top catching the tape as you sew
The horizontal line you see at left it the finished gauntlet edge. The fins are placed onto the template. I trim off the seam allowance so that it leaves 1/2".
The first fin is placed 7/8" from the top of the gauntlet. On Chucks I placed the remaining fins 1" apart along the 1/2" seam allowance. Your amount in between may be different if your gauntlet length is longer or shorter.
Pin securely, because these will want to move on you as you sew them in due to the uneven thickness.
Now sandwich the fins between the two side seams, pin some more between the fins and make sure your top matches exactly, with right sides together sew at 1/2"
This is precisely the way the gauntlets were finished on Adams gloves. A pair of which I had the great pleasure of seeing from Mark Hardeman's collection.
I hope this tutorial helps you to realize your dream of having a pair of replica Batman gloves.