Well in my attempt to learn sub-surface scattering I found this great web site for RenderMan renderers.

The best:

-you have a list of all RenderMan renderers, some of them are even FREE!

-if you are noobie like myself in rendering area this is great site for you.

So take a peek!

https://www.rendermanacademy.com

Well since RenderMan rendering technology is becoming industry standard its wise to start learning some of its basics.