Of course you can negotiate your terms no matter the size you have.
12.5% minus production costs leave you with a very low percentage.
It's always good to have an O&G attorney advise you.
It is also a good idea to get a Lawyer involved because there are so many many other terms of a lease that you don't even think about that you can get screwed on even if you just own the O&G rights and not the land. Even the wording. The leases can say one thing and then they can add on an addendum with seemingly something better but in reality they are still screwing you.
The cost of legal fees would likely consume a good portion of the the royalty and bonus payment on 1.4 acres .
1.4 acres can easily be drilled around. Many examples are documented on well permits on the PA DEP web site. There is no set back requirement for the Marcellus layer since it does fall under the conservation law. (above the Onondaga layer)
I would ask for a no surface agreement.
These is no state minimum in PA. The existing law did not define royalty and hence the court throw it out. The legislature has not bothered to amend the law. It is probably most important to have a cap on deductions of $0.80 MMBTU. Without a cap the royalty rate is somewhat meaningless. There were situations in mid 2016 where landowners were actually paying to have the gas removed.
A reasonable agreement would be 18% royalty with $0.80 MMBTU cap on deductions. In practice this might yield 10% on the point of first sale.
But again 1.4 acres has no bargaining power. Probably most important to get a no surface agreement.
Hopefully your neighbors with more land are savvy enough to talk among themselves and get a bundle of property of 640 acres or more.
Be careful many attorneys are willing to help but know very little.
This is based on first hand knowledge of thousands of acres and many leases.
Getting a gross lease (no post-production deducts) is more important than the actual royalty percentage. Consult an oil and gas attorney, and explain that you would only agree to 15% on a gross lease. He/she should understand your stance, as this is a common negotiating chip.