Section 16B. A student of podiatric medicine who has creditably completed not less than two years of study in a legally chartered medical or podiatric medical school, wherever located, may practice podiatric medicine, but only under the supervision of an instructor in a legally chartered medical, or podiatric medical school, which instructor shall be a registered physician or podiatrist in the commonwealth and a duly appointed field faculty member of a legally chartered medical or podiatric medical college to which the student may be assigned. The board may, in its discretion from time to time designate other facilities or locations in which said student may practice podiatric medicine under the conditions described above. Said student of podiatric medicine shall not prescribe or dispense narcotic drugs as defined in section one of chapter ninety-four C.