In the case of a single proceeding which involves more than one (1) utility, the assessment called for by any special franchise tax deposit order shall be apportioned in accordance with the formula set forth in the Reimbursement Fee Act (D.C. Code § 43-612(b)(2) (1981 Ed.)).
D.C. Mun. Regs. tit. 15, r. 15-1407