Hi,

No, it is not necessary to have the signature of the principal of your school in your class 10th marksheet for counselling. Class 10th marksheet is mainly used for as a proof of your date of birth and if you don't have the signature of your principal, it won't be any hurdle in your conselling. There is a very rare chance of anyone even noticing it so you don't need to worry about it.

I hope this helps,

All the best