That rule is only allowing fotopiccanti.it to link your images, so, its the reverse of what you want.
There are two ways to do it.
1) block all hotlinking allowing your domain
Code:
RewriteEngine On
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?yourdomain.com/.*$ [NC]
RewriteRule \.(jpe?g|gif|bmp|png)$ - [F]
2) deny specific sites from hotlinking
Code:
RewriteEngine on
RewriteCond %{HTTP_REFERER} fotopiccanti.it [NC]
RewriteRule .* - [F]
A better rule that is likely to catch a few potential ways that they can potentially work around your rules is:
Code:
RewriteEngine on
# leave this line in allow empty referrers, remove to disallow empty referrers
RewriteCond %{HTTP_REFERER} !^$ [NC]
RewriteCond %{HTTP_REFERER} !^http://(.*@)?([a-z0-9-]+\.)*yourdomain\.com(:[0-9]+)?(/.*)?$ [NC]
RewriteRule .*\.(asf|mpg|mpeg|wmv|avi|rm|gif|jpe?g|png|zip)$ - [NC,F,L]