Rule 2106. Affirmation of truth of statement by attorney, physician, osteopath or dentist. The statement of an attorney admitted to practice in the courts of the state, or of a physician, osteopath or dentist, authorized by law to practice in the state, who is not a party to an action, when subscribed and affirmed by him to be true under the penalties of perjury, may be served or filed in the action in lieu of and with the same force and effect as an affidavit.