Depends on the directory. Some sites allow them in the article. There may be rules on the number of links allowed within the article body or the position of the link i.e. below the fold. Or leave it in the Author resource box. Google doesn't care where it is.

It is always better to have the links whithin the text. however most article directories don't accept that.

GoArticles and ArticlesBase let you put links in the body of the article. EzineArticle does not