Proof of Service of Process

(a) Proof of service of process must be filed promptly and in any event before action is to be taken by the court or the parties. The proof must show the day and manner of service and may be by written acknowledgment of service, by certificate of the person who served process, or by any other proof satisfactory to the court. (b) Failure to prove service as required by this rule does not affect the validity of service. The court may at any time allow the proof of service to be amended or supplied unless it clearly appears that to do so would result in material prejudice to the substantial rights of any party.