Can Window server Dev CAL mix with RDS User CAL ?

Question

HI

I have 2000 window Server Device CAL , and i need 200 RDS only.

Can i buy 200 RDS User CAL or must follow the CAL type ? i have to buy 200 RDS Device CAL ?

any license compliance if wrong purchase the CAL type ?

By the way, i will using RDS for access Citrix Application