Brooks B17--too narrow in width?

Has anybody else felt that the B17 was too narrow in the seat and/or the outsides the saddle rubbed/pushed into their butt? I like the firmness of the saddle, but I can "feel" the outline of the saddle towards the back pressing into my butt when I ride. I'm wondering if maybe I should've gone for the B68. My sitbones feel supported...it's just the outline "issue". The retailer told me to tighten the saddle underneath and that should "pull the leather under a bit". Anyone else have experience with this??

Yes, that is exactly what happened to me. I rode the B17 for several thousand miles and really liked it....but I always felt my sitbones were maybe right on the edge of the metal under-frame.
'Tightening the saddle' and 'pulling the leather under' would do absolutely nothing to correct this issue. The metal frame of the sit area was simply too narrow for my pelvic bones.
As I rode it more and more that first year, I saw that my sitbone 'dents' in the leather were indeed positioned half way over the frame edge on both sides of the back. That's when I sold the B17 and ordered the B68, and as soon as I got it I knew it was perfect. Happy ever after. Now the new leather sitbone dents are plain to see and they are where they should be- on the leather, not halfway on the frame edges.

It sounds like you're sitting on the cantle (metal frame along the back of the saddle) - no amount of tightening or adjusting is going to fix that. You should probably go with one of the wider brooks.