add_filter( 'spf_field_typography_customwebfonts', 'eapro_field_typography_customwebfonts_modified' );
if( ! function_exists('eapro_field_typography_customwebfonts_modified')) {
    function eapro_field_typography_customwebfonts_modified() {
        // your custom fonts 
        $custom_fonts = array(
            'Alternate-gothic-no-d',
            'Alternate-gothic-no-2-d',
            'Alternate-gothic-no-3-d',
            'Azo sans web',
            'Eskorte-latin'
        );
        return $custom_fonts;
    }
}