The benedictory power of the chants lie more in the awareness and appreciation of their contents, and in the willingness of both the reciters and the listeners to be totally identified with the spirit of their contents.  There should be minimum ritual in these.  The chants are not mantras.

Metta Sutta:

Collection on the Development of Loving Kindness

[The text translated from the Suttanipata - PTS p. 25 – 6, by Bhikkhu Dhammavihŕră]

This is what should be done by one who is skilled in achieving his own goal of peace and tranquility.  He should be efficient and competent, honest and upright, pleasant and polite in speech, gentle in demeanor.  He should be modest and not arrogant.

He should be content and satisfied and be easily supportable.  He should not be over involved, and be simple in his life-style.  He should keep his sense faculties calmed.  He should be wise but not too bold and daring.  He should not be over-attached to households.

He should never resort to doing anything so mean whereby the rest of the wise world would reproach him.  May all beings enjoy happiness and comfort.  May they feel safe and secure.

Whatever living [breathing] things there are, all of those that tremble and those that are steady and strong, whatever are long and large in size, medium, short, minute or massive.

Those that are seen or are unseen, they that live near or afar; those that have already come into being or await birth in any form, may all those living things be blissful and happy.

Let no one ever deceive another.  Nor disparagingly look upon another anywhere.  Either in anger or in hostility let no people wish the unhappiness of one another.

Just as a mother her own child, her only child, guards him at the risk of her life, in the same manner towards all beings, let one develop thoughts of unbounded love.

Loving unbounded thoughts let one develop towards the whole world: above, below and across, unobstructed, without enmity and without hostility and rivalry.

Whether one is standing, moving or seated down, or reclining; as long as he is not fallen asleep, let him develop this mindfulness.  In this Buddhist dispensation, they call it the highest mode of living.

Without taking upon oneself dogmatic views, and being endowed with moral virtue and correct vision, and having gained control over one's greed for lustful pleasures, one comes not to be born in a mother's womb.

Metta Sutta vv. 143 - 152