.htaccess block spam referral traffic?

Hi all,

We've recently seen a surge in referral traffic from domains that feature just a white page with an advertisement. It was suggested that we disavow these links in Webmasters, which we've done, but we would also like to take it a step further as the traffic is impacting other areas of the site.

I've done some searching and it seems we can use .htaccess to restrict access from these spam referrals, is that a safe route to go? I'm worried about making any errors with the .htaccess file so I would greatly appreciate any advice on the matter. Our website is actually on NGINX so we cannot edit a .htaccess file as such but our hosts have asked that we provide the would-be .htaccess changes that they will then change to an NGINX rule.

This is the contents I found from a similar topic but I just wanted to clarify as I'm not sure what the NC,OR and other elements are.

<ifModule mod_rewrite.c>
RewriteCond %{HTTP_REFERER} nym1\.ib\.adnxs\.com [NC,OR]
RewriteCond %{HTTP_REFERER} lax1\.ib\.adnxs\.com [NC,OR]
RewriteCond %{HTTP_REFERER} sin1\.g\.adnxs\.com [NC]
RewriteRule .* - [F]
</ifModule>

There is also another domain that I would like to add but I'm not certain how to do so

RewriteCond %{HTTP_REFERER} a\.rfihub\.com [NC] - Would that be correct for spam traffic from a.rfihub.com?

Any help would be greatly appreciated.

Thanks.