There is an optional prayer for when you dip your fingers into the holy water font.
Most of the time when we dip our fingers into the holy water font, either at church or at home, we simply make the sign of the cross and go about our way. Making the sign of the cross with holy water is a prayer in itself and asks the Holy Trinity to surround us with protection and grace.
However, there is also an additional prayer that can be said (though certainly not required) that is found in the Golden Manual. It is a short prayer that is taken directly from Psalm 51, and perfectly summarizes the symbolism found in using holy water to bless ourselves.
Water is always seen in Christian theology as a means of purification, and so we ask God to cleanse us every time we use holy water. Below is the optional prayer that can lead to a more fruitful experience of dipping your fingers into the holy water font.
Sprinkle me, O Lord, with hyssop, and I shall be cleansed; wash me, and I shall be made whiter than the snow. Create in me a clean heart, O God, and renew a right spirit within me.