Crontab file install error (for WP OBS Plugin)

Hello,
I am trying to setup my first cron job and this is the error I get when I paste the URL into my C Panel:
“-“:2: bad command errors in crontab file, can’t install

It is for a reminder cron job call generated by the WP OBS Plugin.

The cron job URL: */15 * * * * /usr/bin/curl -o temp.txt http://voicelinestudio.com/wp-content/plugins/wp-obs/notifier.php

My website: http://www.voicelinestudio.com

Please let me know if you need any other information.
Thanks so much in advance.
Sarah