You must go yourself to a gendarmerie brigade or a police station or to the competent Court of Justice, with the information relating to the person who will vote for you. You can either pre-fill and print the form, or fill it in on site. If your state of health does not allow you to move, send a letter to the geographically competent unit accompanied by the medical certificate justifying your condition
https://www.interieur.gouv.fr/Contact/Contacter-une-brigade-de-gendarmerie-ou-un-commissariat-de-police For more information and to access the form, click on the following link:
Voting by power of attorney .