For an article marked as 'reviewed' you can't send a message to the creator. The current workaround is to mark the page as 'unreviewed' and then tick the review button again and write a message. This might be fine if you were the original person to review the article, but if someone else originally reviewed it, it sends an annoying message to the original reviewer that you have "unreviewed the article" (note that the Page curation tools do not actually warn you that this message is going to be sent either).
It is also sometimes advantageous to send a message to the creator without marking the page as reviewed.
Please fix and add functionality to simply send a message to the creator without having to mark it as reviewed.
Requested here: https://en.wikipedia.org/wiki/Wikipedia:Page_Curation/Suggested_improvements#52._Allow_patroller_to_send_message_to_editor_without_tagging_or_un-reviewing/re-reviewing
but has also been commented on quite a few times on the reviewers discussion board as being very awkward.