Ideally, a teacher at the school should conduct the speaking tests. Where this is not possible and it is necessary to look for someone outside the school, you should look for someone who is fluent in the language, preferably with teaching experience and with experience of conducting other oral examinations. In the interest of fairness, the person appointed should not have a 'close' relationship with the candidate, and so a parent would not be suitable to conduct the speaking test.
It is important that the person appointed takes the time to familiarise themselves with the requirements of the examination before conducting any 'live' speaking tests. The examination syllabus for the relevant year and a copy of the Teacher's Notes Booklet and Role Play Cards from a previous examination series should be sent to the examiner to read before the day of the examination so that they can familiarise themselves with the general requirements for the conduct and assessment of the Speaking test.
On the day of the examination, you should arrange for the examiner to arrive at the school 1-2 hours before conducting and assessing the first Speaking test, in order that they can prepare the role-play situations and read through the instructions contained in the Teachers' Notes Booklet for the live session.