Dear …
Thank you for interviewing for the position of __(name of position)__ with __(name of organization)__. We have reviewed your qualifications with considerable interest.
You have excellent qualifications as did a number of other candidates we interviewed. We were somewhat overwhelmed by the quality of candidates applying for this position. Although it was a difficult choice to make, we have now made our decision and wish to inform you that the position has offered to another individual.
Once again, thank you for your interest.
Yours truly,