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