Rib / Yarn Question

Hi-
I am making a sweater of sorts that has 8 rows of rib stitch before the main part starts. I am adding a very thin thread of cashmere with the regular yarn to give it a soft look.

Would you add the cashmere to the rib part as well or leave it without? What is normally done?

Thanks!
:XX: KN

I’ve never seen that done, but personally I think I’d add it to the ribbing as well. :thinking: