Add a field to Testimonials Premium

testimonials_widget_premium_form_options.php

add_filter( 'testimonials_widget_cite_html', 'my_testimonials_widget_cite_html', 10, 3 );

function my_testimonials_widget_cite_html( $cite, $testimonial, $atts ) {
	if ( ! empty( $testimonial['is-nurse'] ) ) {
		$cite .= ', <b>' . $testimonial['is-nurse'] . '</b>';
	}

	return $cite;
}


add_filter( 'testimonials_widget_data', 'my_testimonials_widget_data', 10, 2 );

function my_testimonials_widget_data( $data, $atts ) {
	if ( empty( $data ) ) {
		return $data;
	}

	foreach( $data as $key => $testimonial ) {
		$post_id  = $testimonial['post_id'];
		$is_nurse = get_post_meta( $post_id, 'testimonials-widget-is-nurse', true );

		$testimonial['is-nurse'] = $is_nurse ? __( 'Is nurse' ) : __( 'Is not a nurse' );

		$data[ $key ] = $testimonial;
	}

	return $data;
}

				
add_action( 'testimonials_widget_premium_form_save', 'my_testimonials_widget_premium_form_save', 10, 2 );

function my_testimonials_widget_premium_form_save( $post_id, $input ) {
	if ( ! empty( $input['is_nurse'] ) ) {
		update_post_meta( $post_id, 'testimonials-widget-is-nurse', $input['is_nurse'] );
	}
}


add_filter( 'testimonials_widget_premium_form_options', 'my_testimonials_widget_premium_form_options' );

function my_testimonials_widget_premium_form_options( $array ) {
	$array['meta_email']['validate'] = 'sanitize_email,required';

	$is_nurse = array(
		'title' => __( 'Nurse?', 'testimonials-widget-premium' ),
		'type' => 'select',
		'choices' => array(
			0 => __( 'No' ),
			1 => __( 'Yes' ),
		),
		'std' => 1,
	);
	$array['is_nurse'] = $is_nurse;

	return $array;
}


add_filter( 'testimonials_widget_meta_box', 'my_testimonials_widget_meta_box' );

function my_testimonials_widget_meta_box( $fields ) {
	$is_nurse = array(
		'name' => __( 'Nurse?', 'testimonials-widget-premium' ),
		'id' => 'testimonials-widget-is-nurse',
		'type' => 'select',
		'options' => array(
			0 => __( 'No' ),
			1 => __( 'Yes' ),
		),
	);

	$fields[] = $is_nurse;

	return $fields;
}

@michael, We need to update the hooks being used here in the gist.

'testimonials_widget_cite_html' ---> 'tw_cite_html'
'testimonials_widget_data' ---> 'tw_data'
'testimonials_widget_premium_form_save' ---> 'twp_form_save'
'testimonials_widget_premium_form_options' ---> 'twp_form_options'
'testimonials_widget_meta_box' ---> 'tw_meta_box'

Forked: https://gist.github.com/subharanjanm/0264c4aaf8261d4c63be