R.I. Gen. Laws § 9-29-8: Certification as to witness fees.

Every witness before obtaining any fees, except the amount which in certain cases must be tendered to him or her before he or she can be compelled to attend, shall give a certificate to the clerk of the court wherein or before whom his or her attendance shall be given, certifying the number of days he or she shall have attended and the number of miles he or she shall have traveled, in pursuance of a summons issued for that purpose, which certificate shall be subject to the examination of the court, and the allowance shall be made thereon as may be lawfully due; provided, that a certificate may be made for travel and attendance without a summons, in case a witness for the state comes from without the state.