WordPress ACF Multisite location rule

gistfile1.php

<?php

/**
 * 
 * Adds location rule to target specific sites in a WordPress Multisite environment
 * http://www.advancedcustomfields.com/resources/custom-location-rules/
 * 
 */
 
function acf_location_rule_type_blog( $choices ) {
	$choices['Basic']['blog'] = 'Multisite Blog';
	return $choices;
}
add_filter('acf/location/rule_types', 'acf_location_rule_type_blog');

function acf_location_rules_values_blog( $choices ) {
	$sites = wp_get_sites();
	$choices = array();
	foreach ($sites as $key => $value) {
		$blog_details = get_blog_details($value['blog_id']);
		$choices[$value['blog_id']] = $blog_details->blogname;
	}
	return $choices;
}
add_filter('acf/location/rule_values/blog', 'acf_location_rules_values_blog');

function acf_location_rules_match_blog( $match, $rule, $options ) {

	$current_blog = get_current_blog_id();
	$selected_blog = (int) $rule['value'];

	if ($rule['operator'] == "==") {
		$match = ( $current_blog == $selected_blog );
	} elseif ($rule['operator'] == "!=") {
		$match = ( $current_blog != $selected_blog );
	}

	return $match;
}
add_filter('acf/location/rule_match/blog', 'acf_location_rules_match_blog', 10, 3);

?>

Updated here for 4.6