This question comes up all the time and it's easy to understand why.  No one wants to be disqualified!  The goal of the sponsor is to get you to their website where you will look around and perhaps become interested in buying something.  What the sponsors don't like are the bot programs that cruise the web and enter sweeps for you without you ever visiting the site.  Roboform and similar autofill programs are simply typing assistants.  You're still visiting the web, checking out the content, reviewing your entry and so on.  You will not be disqualified for using Roboform.