Hello Aspirant,

Hope you are doing well!

RT(Repeat  in Theory) is the new term assigned by CBSE in 2020 instead of FT (Failed in Theory).This means that the candidate has to repeat the respective subjects or needs to give a re-test to pass in that particular subject.

If you have got RT in a particular subject then that means you have to give a re-test of that subject.

For Example:

Like if someone got RT in physics,then that person will give retest only in Physics.

Similarly,Like you said you have got RT in physics,Chemistry and Maths,then you need to give a re-test in these three subjects not in all the subjects

NOTE:

According to the latest news the CBSE Compartment exams will be held in September 2020

Hope this was helpful!

All the Best!

Keep Smiling :)