In every proceeding filed or pending in the circuit court calling for an adjudication concerning the validity of an issue or proposed issue of tax-exempt bonds the plaintiff shall file with the clerk of the Supreme Court a copy of the complaint accompanied by a letter stating that it is being furnished pursuant to this Rule 14.03. The Supreme Court shall thereupon appoint a practicing attorney as special amicus curiae to participate in the proceeding the same as if he or she were a party opposing the legality of the bond issue, with the right of appeal from any adverse judgment. The trial court shall allow the special amicus curiae a reasonable fee for his or her services, including such as have been performed incident to an appeal, to be taxed as a part of the costs of the proceeding.