At this point in the garment construction, the finished lining has been installed in the outer jacket and a very long seam up both front edges and along collar has been machine sewn, trimmed and pressed. However, the coat is still open at the bottom edge.
Our next step is to create a nice cuff finish.
Put on the jacket to decide where you want the cuff edge to be. A general rule is, with arms hanging down, bend up the wrist slightly and let the sleeve fall to touch the back of the hand.
Mark the desired sleeve length with a pin or chalk. Measure the underarm inseam, and duplicate the length on the other arm as a starting point (it may need a minor adjustment.)
Fold the outer jacket cuff up and pin all around. Next, turn up the lining inside. It will make things easier if you can have someone wear the coat or put the coat on a proper dress form or similar. Allow for a reasonable seam allowance, which may involve some trimming, but the main thing is, you do not want the lining peeking out. Fold it up slightly more that the outer garment.
I didn’t need to trim back the lining much here except a quarter of an inch or so to get rid of the stray fraying ends. I folded up the lining and the outer shell so that the raw ends are together between them. I was careful to line up both sleeve inseams and pin with a couple of pins at that point.
You’ll need to go in-between the lining and the outer shell, and pull the arm open (see photo) to stitch. Baste neatly to test. Flip coat back, try on, and if all is well go ahead and machine sew close to your very neat basting.
Now I am not saying this is the only way to cuff a lined jacket, or even the best, but it is a method that worked OK for me on this project.