I really like the concept of knife sheaths that do more than simply house the knife; I've seen several good ways that sheaths have been use to house additional survival/outdoor gear both in custom and commercial sheaths.
So, with the goal of making my F1's sheath a bit more useful, I've added a firesteel holder in addition to a cord wrap:
Basically, I found a pen that had an interior diameter that matched my firesteel and sawed it down to length so that it was shorter than my firesteel. I then used electrical tape to secure it to the sheath:
After that, I used around 7.5' of paracord to wrap the final assembly.
I ended up using a Primus firesteel which hasn't seen any real use yet instead of my well used LMF one (the Primus is the same diameter as the LMF Scout, but a little longer). Interestingly, I always thought the Primus was a substandard product until I tried it using the spine of my F1. Used this way, it was comparable to the LMF when struck the same way. I guess all it really had was a substandard striker!
One note, this solution alone does not hold the firesteel in place securely. The Primus firesteel uses a thin shockcord instead of regular cord which, when shortened a bit, can then be used to secure the firesteel (this can be seen in the first picture above).
I just did this last night so this hasn't seen any real world use yet.
Finally, on a somewhat related note, I have come up with a good way to carry the knife while backpacking. Taking some inspiration from leather dangler sheaths, I figured out there was no reason the same idea couldn't work with the F1's zytel sheath (or any knife where the weight of the knife is under the top of the belt loop).
I simply tied a piece of paracord in a loop and used that as the dangler. By feeding the loop through the sheath's belt loop, then feeding my belt through the 2 ends of the loop, I had a dangler:
This I did try on my last backpacking trip and it worked great. It enabled me to carry my knife easily both when I was wearing a pack and when I wasn't.