Dear [insert name]
Thank you for your interest in the [insert title] position at [insert Company name]. We appreciate you taking the time to [interview or apply] for this position.
Although we were very impressed by what you have to offer, we are unable to offer you a position at this time. However, we will keep your resume in our current file for consideration at a later date should a suitable vacancy arise.
We appreciate your interest in [insert Company name] and wish you every success in your endeavours.