Add this code to your child theme’s functions.php file:

//Before login form
add_action( 'wpcfe_before_login_form', 'custom_section_login_registration' );
//After login form
add_action( 'wpcfe_after_login_form', 'custom_section_login_registration' );
//Before registration form
add_action( 'wpcfe_before_registration_form', 'custom_section_login_registration' );
//After registration form
add_action( 'wpcfe_after_registration_form', 'custom_section_login_registration' );
function custom_section_login_registration(){
	//Custom Code Here
}

Below example is how to add Nextend Social Login buttons on your Frontend Manager login and registration form

add_action( 'wpcfe_after_login_form', 'custom_after_login_form' );
add_action( 'wpcfe_before_registration_form', 'custom_after_login_form' );
function custom_after_login_form(){
	echo do_shortcode( '[nextend_social_login provider="facebook" redirect="https://wpcargo.com/my-account-2/"]' );
}

LOGIN FORM

REGISTRATION FORM