How do you buy a property off market?

[John Fider]

What I mean is the contract process, not how to find a property.  I'm a realtor in PA so I'm very familiar with the AOS, and what follows, but buying a property that is not on the market and where the seller does not have a realtor... Not sure how different this process is.

Do I use the same AOS contract? Or must I hire an attorney to make our own?  I'd appreciate the step by step process of how you do yours?  Thank you!