If I understand your intention correctly, you are trying to build a one-to-many relationship between RateCard and Country. In other words- a country will have only one RateCard, and a RateCard can belong to many countries. Assuming that's the case, you really don't need the RateCardCountry model (which will be useful if you wanted it to be a many-to-many relationship).
You will need to have:
class RateCard < ActiveRecord::Base
validate :name, :presence => true, :uniqueness => true
belongs_to :rate_card
end
And make sure you have county_id foreign key in the RateCard table.
and then:
class Country < ActiveRecord::Base
has_one :rate_card
end
Also, it seems that right now you have:
class Country < Geography
I am not sure if you are subclassing from a Geography class, as you have not provided the rest of the code.
Hope that helps.