Assuming you have a Protection Paladin, and a Holy Paladin in the raid, WHY do you need a Ret Paladin?
Attack Power Buff (Flat Add): Battle Shout, Blessing of Might
Percentage Haste Increase (All Types): Improved Moonkin Aura, Swift Retribution
Percentage Damage Increase: Ferocious Inspiration, Sanctified Retribution
Critical Strike Chance Taken Debuff (All types): Heart of the Crusader, Totem of Wrath
Stat Multiplier Buff: Blessing of Kings
The Holy Paladin uses Kings, and the Protection Paladin has Blessing of Sanctuary, way more reliable than Grace.
Moonkins have 3% haste, Sanctified Retribution is more reliable than Ferocious Inspiration so that may be the only use.
Everything else is replable, and a GOOD Rogue, Warlock, Shadow Priest, or Mage will beat a good Ret Paladin any day of the week. Not to mention 3 of those four classes have range.