Rho-dependent termination is not fully understood but there’s a brief description in almost every concerned book about it.
In Snustard and Instant notes-Molecular Biology it is written that, the rho protein binds a stretch of 72 nucleotides at the 3' end of the nascent RNA, which could be a recognition site and then moves along 5' -> 3' direction separating the DNA-RNA hybrid.
But how's it possible, rho binding to 3' end (which is not free) and moving in 5'-> 3' (if so it is sure to fall off!)?
Diagram from Berg showing something opposite, i.e. it has attached to the 5' end and is moving in 5' -> 3' direction.
What is the right thing?