Psychometric tests are also referred as instruments of measuring or assessing. The selection of the tool/instrument would depend on "what do you want to measure" - the factors or the purpose. The first step to employ psychometric tools is to determine the factors and the levels which you wish to measure and then choose the tools or tests. Say you have a vacancy for sales position and want to find out the personality frame of the person applied for sales position. You will have to determine the factors essential for this job / position. Lets assume that this job needs the person to be socially bold. Now you need to find out his social boldness and the level of it. In this case you would use 16 PF as this test measures it and not MBTI as this test does not measure it.
Many a times we use the terms psychometric tools and personality tests interchangeably. Its correct partially and not wholly.
There are various conceptual basis and theories on which the personality tests are based on. Where as 16 PF is a trait based theory , MBTI is a type based theory. It would benefit you if you first read a bit about the theory on which the test is based upon and then decide to use the test. Psychometric tools are very powerful and incorrect administration would result in errors.
Second, to make 16 PF relevant for the interviewer you should interpret the results and connect it to the job situation.
Eg. in case of 16 PF, say the person scores 9 on factor A, warmth, which means outgoing and warm. Presence of this factor will have different implications and applications for different jobs. The reports generated will be of generic nature, its advisable not to present only the report but your interpretations as well. This will help the interviewer ask more relevant and structured questions.