I did a post awhile back about attractive women and I posted a picture showing a woman's tummy and her hip bones. I personally love feeling and seeing my hipbones and think it's sexy. But, I wanted to hear/see other women's idea of "too skinny".
For me personally on my frame to skinny is below 135-130lbs, is too skinny.
It depends everyone carries their weight differently.
I do like seeing a bit of hip bone, but not on me lol my hips are odd due to a few surgeries.