Hi Steve!
I'm sorry for the delay in responding to your query. I was hoping another member might answer.
The Randall " Trapper", Model #25 with a 5 inch long blade is, I believe one of RMK's most popular knives.
Since "imitation is the sincerest form of flattery", I'm glad one of your customers has chosen this model for you to try and replicate.
Here's some photos of mine when it was brand new way back in 2005. It's a user now:
Now as to the width of the blade from the spine to the edge, at it's widest point it is 1 5/8 inches. Of course thee blades are hand forged and measurements will vary slightly
I hope this helps and good luck with your efforts.
Please be sure to post an image of your finished product!
Cheers!
David
P.S. Geez I love this knife!!!