Under the sink I have a reverse-osmosis filter which provides water to a small dedicated faucet on the sink.

There is clear plastic tubing which is attached to the RO filter piping, and runs along behind the cabinetry. Up until recently it was attached to the ice maker of the now-deceased refrigerator.

The new refrigerator has no ice maker.

I want to attach a shut-off valve to the clear plastic tubing at what would be the refrigerator end. I want to leave the tubing in place behind the cabinetry so that I can perhaps someday add an icemaker.

Can you advise on what kind of cutoff valve and related parts I need, as well as the steps involved?

Thanks! Jackie