How would you make an "OnTouch" damage script?

Hey, guys. I am trying to make a localscript that whenever Player A presses "f", it does a little animation, and any other players that touches Player A's right arm will lose 70 health. The following is in a Localscript, inside StarterPack:

Player = game.Players.LocalPlayer
mouse = Player:GetMouse()

db = false
function onKeyDown(key)
key = key:lower()
if db == false then
    db = true
    if key == "f" then -- when F is pressed...
        --Make a little animation.
        local RightShoulder = Player.Character.Torso["Right Shoulder"]
        local LeftShoulder = Player.Character.Torso["Left Shoulder"]
        for i = 1,10 do
            RightShoulder.C0 = RightShoulder.C0 * CFrame.Angles(0,0,0.5)
            LeftShoulder.C0 = LeftShoulder.C0 * CFrame.Angles(0,0,-0.5)
            wait(0.001)
        end
        for i = 1,10 do
            RightShoulder.C0 = RightShoulder.C0 * CFrame.Angles(-0.5,0,0)
            LeftShoulder.C0 = LeftShoulder.C0 * CFrame.Angles(-0.5,0,0)
            wait(0.001)
        end
        for i = 1,10 do
            RightShoulder.C0 = RightShoulder.C0 * CFrame.Angles(0.5,0,0)
            LeftShoulder.C0 = LeftShoulder.C0 * CFrame.Angles(0.5,0,0)
            wait(0.001)
        end
        for i = 1,10 do
            RightShoulder.C0 = RightShoulder.C0 * CFrame.Angles(0,0,-0.5)
            LeftShoulder.C0 = LeftShoulder.C0 * CFrame.Angles(0,0,0.5)
            wait(0.001)
        end
        --locate the player's right arm and damage whomever touches it
        local RightArm = Player.Character["Right Arm"]
        local p = game.Players:FindFirstChild(RightArm.Touched.Name)
        if p and p.Character.Humanoid then
            p.Character.Humanoid.Health = p.Character.Humanoid.Health - 70
        end
    end
    db = false
end
end
mouse.KeyDown:connect(onKeyDown)

If anyone could tell me what I did wrong, I would highly appreciate it! ALSO: The animation part works fine. The only problem is that it doesn't do damage to others.

Thanks!