Okla. Stat. tit. 40 § 79
The age and schooling certificate shall be approved by the principal, headmaster, or equivalent administrative officer of the school which the child attends or should be attending or by one of the child's parents if the child is being schooled at home, who shall, for the purpose of this article, be empowered to administer an oath. The principal, headmaster, or equivalent administrative officer of the school which the child attends or should be attending or by one of the child's parents if the child is being schooled at home, shall approve such certificate only upon the application in person of the child desiring employment accompanied by its parents, guardian or custodian, and after having received, examined and approved documentary evidence of age, showing that the child is fourteen (14) years of age, or over, which evidence shall consist of one of the following named proofs of age, duly attested, and the proof accepted shall be specified in the certificate issued to the child; the proof specified in subdivision (a) shall be required first, but if this is not available then one of the proofs specified in the succeeding subdivisions shall be required and in the order designated until the age of the child be established, as follows:
Every employment certificate shall be signed, in the presence of the officer issuing the same by the child in whose name it is issued.
Okla. Stat. tit. 40, § 79