When I was looking for what to put i did check the chanting book on Access to insight which has two one for a group and one for an individual
(When one person is asking forgiveness)
Repeat Namo... three times. Then:
[Mahāthere]* pamādena, dvārattayena kataṃ,
Sabbaṃ aparādhaṃ khamatha me bhante.
Venerable Sir, may you forgive me for any wrong I have done you out of carelessness in thought, word, or deed.
[* Mahathere is used for very senior & highly respected monks. Change it to There for somewhat less senior monks, Upajjhāye for one's preceptor, Ācariye for one's teacher, and Āyasmante for monks in general.]
Bow down & stay there while the monk says:
Ahaṃ khamāmi, tayā pi me khamitabbaṃ.
I forgive you; may you all also forgive me.
I forgive you, Venerable Sir.
The monk will then recite a blessing, after which say:
Very good, Venerable Sir.
BOW THREE TIMES
It seamed a bit pretentious to use this one as it was automatically giving forgiveness so I opted for the one above which I found here http://www.chantpali.org/closing.html#khama_yacana
Blog, Suttas, Aj Chah, Facebook.
He who knows only his own side of the case knows little of that. His reasons may be good, and no one may have been able to refute them.
But if he is equally unable to refute the reasons on the opposite side, if he does not so much as know what they are, he has no ground for preferring either opinion …
He must be able to hear them from persons who actually believe them … he must know them in their most plausible and persuasive form.John Stuart Mill