Your AddRatingButton types are incorrect.
You have three commands to deal with (minus Thumbs buttons, because you're not asking about those 🙂 )-
AddButton(Integer id, String title) ' this one is used for Play, Resume, Loop, and your standard usual buttons - it's also the same on the springboard as for dialog boxes - you should already have some of these
AddRatingButton(Integer id, Integer userRating, Integer aggregateRating) ' This is the 5 star 'rating' button you are asking for - it is used on the Netflix details screen with automatic control of 'liked it'
SetStaticRatingEnabled(Boolean isEnabled) 'This controls display of the static rating information for the content item and shows up near the synopsis of the content item - the user can't change the value directly for these stars
The star rating can show either community StarRating (red) or UserStarRating (yellow). If both values are set, the control will display the UserStarRating.
So, when setting up your screen, usually the setstaticrating is set to False to allow more room for actors - if it's true and no value is set, then you see 5 empty stars for it when the user rating is 0 or unset. If it is set, it duplicates the user rating value (0-100). If you're not using the user rating at all, then the static rating shows the community rating (average). You'll need to play with it to understand more.
On your springboard screen, buttons are placed in the order they appear, - where screen is your handle for the current display screen
screen.AddButton(1, "Play/Resume")
screen.AddButton(2, "Play from Beginning")
screen.AddRatingButton(3, 0, 50) ' sets button 3 to a user rating of 0 for unrated by the current user, and 50 for the baseline - 50 being the 'average of all user ratings so far'
When button 3 is clicked, you will want to send the value to the server database to log the user selected value, and then average all the values for the content item to return future versions of the xml containing the result to users accessing this page so the 'aggregateRating' is current. - so the 50 value could just as easily be changed to something like screen.AddRatingButton(3, show.currentuserrating, show.userstarratingaverage) to be referencing the content's xml information to populate.
You'll need to handle that like you handle the other buttons and server interaction for your channel.