App icon for Mac 10.5

Hi All

When launching my app on Mac 10.5, the icon is not shown in the dock.
I'm using introjucer to export xcode project, there are 2 icons to mention: small and large.
I'm currently using 64x64 for the small, and 512x512 for the large.

Anyone here knows the required sizes for both small and large icons, that will display properly from Mac 10.5 to the most recent versions ?