PA follows the Federal rules for inheritances, as far as whether the inheritance is taxable on your return or not. For example, if you inherited stock and then sold it, that's already entered in the Federal return and transfers to PA. You may be thinking of inheritance tax but that has nothing to do with PA taxable income on your tax return.
If what you inherited is cash, that may be subject to inheritance tax in PA but not income tax. You only need to enter this amount in the interview for the Special Tax Forgiveness credit where it asks for nontaxable income. See the screen shot below for where to enter it.