Writing letter to bishop.

[aquinas138]

If one were to write a letter to a bishop who does not possess ordinary jurisdiction, e.g., a bishop of the SSPX, are there any differences in formal address? For instance, what would be the proper closing to the letter? I have seen in some traditional etiquette guides the suggestion to close with "Kissing the Sacred Ring" when writing a bishop; is this appropriate? I guess I am unsure of the exact symbolism of the ring itself, whether it indicates the union between the bishop and his see, which some bishops do not possess. Would something like "Asking Your Excellency's blessing, I am Yours, respectfully" be more appropriate?