Does the preceptor/supervisor need to sign the affiliation agreement or just a representative from the institution?

The preceptor/supervisor does not need to sign the affiliation agreement. The person signing must have the authority to sign on behalf of the facility and their employees. For example, at a high school, signing authority might reside with the principle or superintendent, at a clinic it might be the CEO, etc. For colleges/universities, it is usually a president, dean or their designee. There may be a contracts office at the college/university that handles these types of agreements. Remember if the preceptor is employed by one facility (i.e., a clinic) and is supervising students at another facility (i.e., a high school) then there must be an affiliation agreement or MOU on file for both facilities.