Reference this documentation: Icons
It says “ At a bare minimum you’ll want to include PDF’s images for light mode icons so they can be used for all views where your Component appears within the RapidWeaver Elements UI.”.
Do you mean PDF images or should that be PNG?
I don’t have Sketch (it seems expensive, to me anyway). Will a simple .icns file creator do the same job reading say a source image of 1024x1024 size to generate the .icns file?
Nope, we do mean PDF (they are a scalable format, unlike png), make sure the graphic you use is also on a transparent background.
This is how they appear in our Button component in Elements (see screenshot below), and here’s a zip file containing the button pdf icons for your reference.
So we don’t need a .icns file?
Nope, you no longer need those. Just the icons I supplied above. (I’ll get the icon docs updated too).
@logrunner The icon docs page has been updated. Let me know if you need further clarification on anything.
It’s interesting. For those of us that loved NeXT, display postscript was one of the best things it had. Much of that came forward to MacOSX when NeXT was rebranded to Apple. But some things were lost due to compatibility issues and shear processing power requirements. PDF icons is one of those technologies that just make the MAC work. Glad it’s in Elements. 
