If you have set your survey to collect location information, Presto will try to get the evaluator's location before unlocking the survey, and will include that information in the evaluation.  To see where the evaluator was, go to to the Completed Evaluations report (Results -> Completed Evaluations) and click the evaluation ID.  The distance between the evaluator's geolocation and the target location is displayed in the evaluation header, as well as the geolocation timestamp:

To see the target location and the evaluator's location on a map, click View Map Location: