Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
This card is used to Ritual Summon "Dokurorider". You must also Tribute monsters from your hand or field whose total Levels equal 6 or more.
--スカルライダーの復活
--Revival of Dokurorider
local s,id=GetID()
function s.initial_effect(c)
	Ritual.AddProcGreaterCode(c,6,nil,99721536)
end