Fla. Stat. § 696.03

No contract or agreement or other instrument purporting to contain an agreement to sell or purchase real estate, which has been executed by an agent or attorney in fact shall be recorded in any of the public records of this state, unless the authority of such agent or attorney in fact to execute the instrument sought to be recorded is produced and recorded by the recording officer, or is already recorded in the county where such instrument is sought to be recorded; and for the purposes of ss. 696.01-696.04 no authority for the execution of instruments by an agent or attorney in fact shall be accepted which is not executed in the manner provided by law for the execution of deeds.