Gst under rcm on local transportation charges

We send goods in small lots (say 200 to 500kg) for job work to a local electroplating company. We hire tempo which is operated by an individual person and we pay him in between Rs 300 to Rs 500/- per lot transported. The owner of tempo don't issue any G.R. /document. We pay him in cash against his signing the cash voucher.

Are we liable to pay RCM on this ?

Further, what would be SAC code for job work done by electroplating company?

Thanks for your help !