Your frame is shown but it doesn't contain anything, try adding a background and have a look again
Code:
local backdrop = {
bgFile = "Interface/Tooltips/UI-Tooltip-Background",
edgeFile = "Interface/Tooltips/UI-Tooltip-Border",
tile = true,
tileSize = 16,
edgeSize = 16,
insets = { left = 4, right = 4, top = 4, bottom = 4 }
}
SK.Frame:SetBackdrop(backdrop)
Also when you register ADDON_LOADED it will also fire for every addon that loads after yours so you might want to unregister it after you're done.
Code:
SK.Frame:UnregisterEvent("ADDON_LOADED")