On the third repetition, raise and prolong your voice, then add:
سُبْحَانَ المَلِكِ القُدُّوسِ
Subḥāna l-maliki l-quddūs
Glory be to the King, the Most Holy.
رَبِّ الْمَلَائِكَةِ وَالرُّوحِ
Rabbi l-malāʾikati wa ar-rūḥ
Lord of the angels and the Spirit.