Damage when Touched?

wait(0.01)
local enabled = true
Player = game.Players.LocalPlayer
character = Player.Character
mouse = Player:GetMouse()
run = game:GetService("RunService")
RS = Player.Character.Torso["Right Shoulder"]
LS = Player.Character.Torso["Left Shoulder"]

function onKeyDown(key)
    key = key:lower()
    if key == "x" then
        for i = 1,5 do
            RS.C0 = RS.C0 *CFrame.Angles(0, 0, 0.5)
            wait()
        end
        for i = 1,5 do
            RS.C0 = RS.C0 *CFrame.Angles(0, 0, -0.5)
            wait()
        end
        for i = 1,5 do
            LS.C0 = LS.C0 *CFrame.Angles(0, 0, -0.5)
            wait()
        end
        for i = 1,5 do
            LS.C0 = LS.C0 *CFrame.Angles(0, 0, 0.5)
            wait()
        end
    end
end

mouse.KeyDown:connect(onKeyDown)

How do i add damage so that when the fist touch someone they get 5% percent of damage?