milkAdminRTK.jar and MCSignOnDoorRTK.jar are not bukkit plugins! Are RemoteToolkit modules.
Place this jar in the module folder of your toolkit.
Not required to use milkAdmin plugin but add good features.

RemoteToolkit: http://forums.bukkit.org/threads/674/

Instalation:

1-Copy milkadmin.jar and milkAdmin folder to plugin folder.
2-(Optional) Copy modules in Extras folder to RemoteToolkit modules folder. ( {MC Server}/toolkit/modules/ )
3-Start or restart the server.