Adding a Miscellaneous Option on new thread post

[glennybee]

Hi,

I am looking to add an option to the Miscellaneous Options part of a new thread post.

I have set up my forum so that members can claim authorship via their google plus profile of any threads they create.

I want to add an option to the Miscellaneous Options saying "Claim google authorship of this thread."

And all it needs to do if it is checked, is add a rel="author" tag to the username link on the first post of the thread.

Would i do this with a plugin or what?

Thanks so much in advance