Thank you for your fast response!!
I see other option using some code like this:
add_filter( 'the_content', 'my_the_content_filter', 0 );
function my_the_content_filter( $content ) {
if ( is_single() )
{
global $post;
$pgLnk=get_post_meta($post->ID, 'Button', true);
$content .= 'CODE WHAT U WANT TO ADD HERE';
}
return $content;
}
but I don’t know how implement my code here, or if is posible…