Hi again,
This is the code I used to create the frontend form:
$options = array(
'id' => 'photo-athlete',
'fields' => array( 'photo_athlete' ),
'form' => true,
'submit_value' => __("Sauvegarder votre photo", 'acf'),
'instruction_placement' => 'field',
'updated_message' => false,
'uploader' => 'wp'
);
acf_form( $options );
Thanks
Philippe