help

hi everybody ,
i devlopped a widget to select cities and i integreted it to a new a content type..all thing seem to be fine but when i try to use SEARCH API i dont found this field in the liste of the fields when i want to define the index
i tried "Add related fields" below but cant found it
i already integred a widget to select a country that i could see it in the list of the fields when i define the index in search API...
so why my widget dont appear?...and how can i do it.?...should i impilment some other hook to my widget to do this..?

thank you for all your participation