In some cases, a signer may simply need a Notary Public to administer an Oath or Affirmation orally, rather than as part of a Jurat, affidavit or other written document. The purpose of administering a verbal oath or affirmation is, again, to compel the signer to truthfulness.
An Oath is a solemn pledge to a Supreme Being. An Affirmation is a solemn pledge on the individual's personal honor. The choice between an Oath or Affirmation should be made by the signer.