Does runway models have big or small body frame?

Small frame mostly

Small frame? I don't think so. It really depends on the model, but I would think runway models generally have large to medium frames because their bones protrude. A tall, thin, small-framed person wouldn't have bones protruding as much (even though he or she may be very, very, thin).

In other Words, large-framed folks may weigh more because of their bigger & heavier framed bones, but they would look a lot thinner even at higher weights (since more bone is taking up space rather than fat, regardless of how little or much actual fat the person is carrying).