obs.icns now corresponds to Table 5-1:
icon_512x512@2x - 1024 x 1024
icon_512x512 - 512 x 512
icon_256x256@2x - 512 x 512
icon_256x256 - 256 x 256
icon_128x128@2x - 256 x 256
icon_128x128 - 128 x 128
icon_32x32@2x - 64 x 64
icon_32x32 - 32 x 32
icon_16x16@2x - 32 x 32
icon_16x16 - 16 x 16