How would I create an LNA layout design when using the s2p file on the schematic?

The s2p file component only has 3 pins, and the ADS model has 4 pins (which seems more realistic to the actual component ex. ATF-55143 has 4 pins). How would I know how the s2p file was formed on a layout of its own, when all I would only be dealing are 3 pins from the s2p file? When I design my LNA I do not want to mess up my design, by thinking that my two source pins (pins 2&3 on the ATF-55143) will comply to the actual s-parameters on the s2p file, when I placed different lengths of line and had different amount of vias on each source pins. I do not want to mess my design up when I get it manufactured again. Maybe I do not need to create a layout design, what do you say?