R.I. Gen. Laws § 34-16-12: Service on defendants unknown or with unknown addresses.

Service of process upon all unknown defendants, resident or nonresident, or others known, but whose names or addresses are unknown to, or unascertained by, the plaintiff shall be made by publication of an order of notice, to be entered by the court in some public newspaper published in this state, to be designated by the court, for such length of time as the court shall direct.