propane line installation
Is that the only thing that will run on propane? 

The amount of other appliances and length of run determine pipe diameter.

I have propane in my place and it starts with 1" outside the house @10 PSI, then it hooks to a regulator that goes down to 3/4" Corrugated stainless steel (CSST) and 1/2 PSI. Then from there it branches out to all my appliances in 1/2" CSST by means of connectors that allow the branching off to other sizes. That does not mean it will work with what you need, these systems are usually designed, but you could prep for the largest possible diameter...