Sec. 4. Service of notice of appeal. – If personal service of the copy of the notice of appeal can not be made upon the adverse party or his  counsel,  service  may  be   done  by  registered  mail  or   by substituted service pursuant to sections 7 and 8 of Rule 13.
Sec.  5.  Waiver  of  notice.  –  The  appellee  may  waive  his  right  to  a notice that an appeal has been taken. The appellate court may, in its  discretion,  entertain  an  appeal  notwithstanding  failure  to  give such notice if the interests of justice so require.