I used about a 3/8 seam, but honestly did not have any problem with ravelling. I'm keeping this one for myself, so I guess I'll find out if it's a problem. I just put together the back of another quilt with gray linen, and this time I used about 1/2 seam, then serged it - so not concerned at all about that one. Now, just to figure out how to quilt it.
I bought the linen fabric to sew clothing, but haven't decided what to make with it yet.