I would like to put the rear end of the rvf onto my vfr. will it fit straight on ?

Yeah but you will need RVF subframe, VFR will not take RVF bodywork.
Other than that easy job.

Aly

I've put an RVF seat unit onto a VFR subframe in the past (race glass). The mounting holes are different and you'll need to pack between the seat unit and subframe a tad. Mock fit it and you'll see what is required.