Mod_rewrite to direct subdirectory to another URL

I am trying to play with Apache Mod_rewrite and I cant get this to work.

I want to redirect

xyz.com/blog to xyz.wordpress.com

I edited the .htaccess file to add this line.

RewriteRule ^blog/?$ http://ift.tt/1LWb5Y6 [NC]

But it doesnt work.