Hi,
It's possible, I do this myself occasionally.
I use a VGA to Composite converter, my modulator has composite, which converts it to RF. I'd assume the Macbooks have VGA out.
https://www.ebay.co.uk/itm/PC-Laptop...72.m2749.l2649
https://www.amazon.co.uk/dp/B018LKA4...ing=UTF8&psc=1
I'm not associated with either seller, these are just what I use, and could be an option for you.
Hope that helps
'77