Thanks very much to everyone who responded to yesterday's post. Turns out there are quite a few possible ways forward! After some contemplation, I finished tatting round 10. I don't like it as an outer row, I think the outward facing rings make it look incomplete. I had a look at the photo of the finished doily on Renulek's blog and took a design element from round 12 or so to create an outer row. I've only just begun and it's possible it'll need a bit of tweaking, but I think it will work.