Blocking external image Hotlinks

[motowebmaster]

Trying to keep other sites from hotlinking to my site's images.

I've been working with the following in my vhost.conf file. If I remove the # signs on the respective four lines, run the reconfig psaadmin and restart apache, which will restart successfully - but none of my images will appear on my website:

Options +FollowSymlinks
RewriteEngine On
RewriteCond % !^$
RewriteCond % !^http://domainname.net/.*$ [NC]
RewriteCond % !^http://www.domainname.net/.*$ [NC]
RewriteRule \.(gif|jpg|jpeg|png|swf)$ - [F,NC]

Below is what SwSoft's Knowledgebase states to do in vhost.conf:

RewriteEngine on
RewriteCond % !^$
RewriteCond % !^http://(www\.)?MY_DOMAIN\.COM(/)?.*$ [NC]
RewriteRule \.(gif|jpg|jpeg|png|swf)$ - [NC,F]

Which I tried as well, with the same results. Initially I thought that making the lines less complex it would help - but no dice.

Any thoughts?