What equipment do you have? What I like to do is a rough profile first then drill my screw holes. Get my profile to a 220 grit making sure to keep the bottom flat under where it will attach to the scale. I then start the spring on the underside with the upper grinder wheel. I like to keep this curve of the spring on the tip side of the clip to allow it to come out of the pocket easier. On the other end of the spring towards the screws I like to make a right angle to accommodate the pocket better. I do this part on my mill and follow up with a flat file. Also, make sure you bevel the very tip or it won't get in your pocket. If you are limited on equipment you can do the whole thing with files.
Next comes sanding everything up to 3000 grit for me and then a buff. Anything that doesn't look right will show up. At this point it should be very attractive and shiny!! Carefully and slowly torch with propane. Any mistakes can usually be removed with polish and another attempt can be made with the torch as long as it didn't get too hot and too far past blue on the spectrum. Attach and admire.
There is more finesse to it but it's a lot of trial and error. Getting the tension right is just something you have to play with but I like them fairly stiff. You don't need much flex in it to get it into your pocket as long as you beveled a good ramp at the tip. Hope this helps.
I usually countersink the screw heads but thought I'd try something different on this one.