Best practice for creating icons for toolbars?

I’m going to need to create several icons for use in Rhino toolbars. I have nice high-resolution .PNG and .SVG files that I can easily render into smaller .PNGs, and am wondering about the best way to provide those to my toolbar button. Do I need to provide all three sizes or will Rhino itself resize a provided 32x32 to generate the smaller sizes? I’d experiment, but I don’t know how to force Rhino to use a particular toolbar icon size (and can’t imagine how I’d even be able to see a 16x16 icon anyway!). Thank you!

I wound up using ImageMagick to convert my large icons into all three sizes, and then importing each separately into the appropriate resolution in the Rhino icon editor. Figured out how the images are stored in the .rui but didn’t take the time to try to automate that build process and bypass the UI. Thanks anyway!