Rf 70-200

[Arapaj2010]

I have the rf 70-200 

Someone knows if the 2 x extender works on it

[March411]

If you have the new RF70-200mm F2.8 L IS USM Z the extenders are compatible.

https://www.usa.canon.com/shop/p/rf70-200mm-f2-8-l-is-usm-z?color=White&type=New

The older RF70-200mm F2.8 L IS USM cannot use extenders

[ebiggs1]

Just because it will mount does not mean you should. In photography you always pay a penalty to get something. There is no free lunch. IMHO, I would not, I mean, I would never do it.