I have my lovely Nik's Wallet in Viridian on a key strap - it means I can always fish it out of my bag with ease and I'm less likely to lose it. Unfortunately less likely doesn't mean that it's impossible, and my skill with regards to losing things is unparalleled (if you've seen my ukulele please let me know!)–and some of my bags aren't Tom Bihn and don't have O-Rings!
For this reason, I wanted to attach a Tile to my wallet, I clipped it onto the key strap first but the attachment on the Tile is quite large and after finding my Tile in my coat pocket but spending another 15 minutes looking for my wallet I decided enough was enough. I found some tiny split rings (keyrings) which are just 5mm in diameter (0.2"). This goes onto the webbing hook of my wallet easily, and the Tile is attached to that! It's simple but works for me. I did consider getting one of the credit card shaped Tiles, but I don't like that you can't replace the batteries in those and it would use up precious space inside my wallet. I can also detach my wallet from the key strap and keep the Tile attached now.
As a bonus, this also solves the fact that the attachment on my KeySmart Pro is too small for my key strap! I put another of the tiny rings on the attachment and the key strap attaches handily!
Unfortunately I can't seem to upload images to the forum, but I've put them in Dropbox instead:
Nik's #4 Wallet
KeySmart Pro
I thought I'd share in case anyone else has the same problem I do! Now where is that ukulele...