Weber will not warrant putting an OCR onto a board.... epecially with Rend Aid..... It is far too rigid, and will crack.
There are applications for OCR, but onto a board is not one of them... (although, I bet a lot of you guys have done it...)
Use a product / system fit for the application. Boarded render applications are for framed buildings (timber and SIP mainly, but some SFS), all of which will move and settle over time (brick and block builds are not suppost to settle - but some foundations will drop) - hence the use of suitably flexible materials on builds that will move.
As JFE has pointed out, the m2 prices for materials are not that different, and they are all a minimum of 2 day render applications....