I modified the existing Winamp skin in Enigma for Rainmeter to show Spotify songs as well. Attached is the zip file of that mod. All you need to do is extract the three files to the already existing folder Enigma\Sidebar\Music\Winamp in your Rainmeter skins folder and refresh all skins.
This skin will use Winamp if it’s on else it will show the spotify status. It will also support Foobar2000 when it’s made to emulate Winamp by using following plugins.