Since these methods are easily covered everywhere online and in textbooks, I will assume you are looking for updated methods and techniques. So with that...
Transcription rates cannot be measured by normal RT-qPCR through total RNA extraction, that will only give you steady state levels relative to some arbitrary baseline.
If you actually want to measure transcription rates perform a nuclear run on as would be done in GRO/PRO-Seq, and then do qRT-PCR or sequencing.