How to specify penalties for breaking lease on lease agreement?

[Franklin McGuire]

Hi all, I'm new to property management and trying to get a lease signed for the first property I've picked up to manage. I'm in Charleston, SC and am using this residential lease agreement. My question is: I see on here where I state the end of the lease, but I don't see on here where I can specify penalties (a fee, for example) if my new tenants want to break lease and move out early. Should I just handwrite this into the "Additional Terms" section at the end of the agreement? 

Thanks for the advice!