Looks about right, but you need to create the texture before you apply it.
Example
lua Code:
-- -- can change OVERLAY if you want another to use another framestrata
Local BorderTL = SK.Frame.Options:CreateTexture(nil, "OVERLAY")
BorderTL:SetTexture([[Interface\PaperDollInfoFrame\UI-GearManager-Border]])
BorderTL:SetWidth(64)
BorderTL:SetHeight(64)
BorderTL:SetPoint("TOPLEFT", 0, 0)
BorderTL:SetCoords(.5, .625, 0, 1)