Example adding a meta box to CPT Archive Settings page, saving and loading values.

snippets.php

<?php

add_filter( 'genesis-cpt-archive-snippet', 'cs_add_additional_field' );
/**
 * Add additional field to the Genesis CPT Archive Settings array for snippet post type.
 *
 * @param array $default_settings
 * @return array modified default_settings
 *
 */
function cs_add_additional_field( $default_settings ) {
	$default_settings['additional_field_name'] = '';
	return $default_settings;
}

add_action( 'genesis_settings_sanitizer_init', 'cs_register_additional_sanitization_filters' );
/**
 * Add Sanitization using Genesis Add Option Filter
 */
function cs_register_additional_sanitization_filters() {
	genesis_add_option_filter( 'no_html', 'genesis-cpt-archive-settings-snippet',
		array(
			'additional_field_name',
		) );
}

add_action('genesis_cpt_archives_settings_metaboxes', 'cs_register_additional_settings_box');
/**
 * Register Additional Metabox
 *
 * @param string $_genesis_theme_settings_pagehook
 */
function cs_register_additional_settings_box( $_genesis_theme_settings_pagehook ) {

	if ( 'snippet_page_genesis-cpt-archive-snippet' !== $_genesis_theme_settings_pagehook ) {
		return;
	}

	add_meta_box('cs-additional-settings', 'Additional Settings Box', 'cs_additional_settings_box', $_genesis_theme_settings_pagehook, 'main', 'high');
}

/**
 * Create Metabox function, called from cs_register_additional_settings_box
 */
function cs_additional_settings_box() {
	?>

	<p>Additional Field:<br />
		<input type="text" name="genesis-cpt-archive-settings-snippet[additional_field_name]" value="<?php echo esc_attr( genesis_get_option('additional_field_name', 'genesis-cpt-archive-settings-snippet') ); ?>" size="50" /> </p>

	<?php
}