GIRM 84-89 addresses the Reception of Communion, and also what takes place immediately afterward:
84. The Priest prepares himself by a prayer, said quietly, so that he may fruitfully receive the Body and Blood of Christ. The faithful do the same, praying silently.
Then the Priest shows the faithful the Eucharistic Bread, holding it over the paten or over the chalice, and invites them to the banquet of Christ; and along with the faithful, he then makes an act of humility, using the prescribed words from the Gospels.
85. It is most desirable that the faithful, just as the Priest himself is bound to do, receive the Lord’s Body from hosts consecrated at the same Mass and that, in the cases where this is foreseen, they partake of the chalice (cf. no. 283), so that even by means of the signs Communion may stand out more clearly as a participation in the sacrifice actually being celebrated.[Eucharisticum Mysterium 31, 32; Immensae Caritatis 2]
GIRM 85 is one of the flashpoints for good liturgists everywhere: how to balance good planning at every Mass against the desire to be prepared for eventualities.
Catholic Sensibility 