بسم الله الرحمن الرحيم
(Fatwa: 1137/1064/M=9/1439)
You are a Hanafi so you should lead witr salah according to Hanafi School of Fiqh. According to Hanafi Fiqh witr salah is three rakah with one salam. However, those who pray behind you their salah will be valid without any karahat though they follow Shafai School, you should not worry.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
