Pretty much any MOSFET will do. If you are switching, say, a 20V power source with a load current of 5A, you need a FET with a VDS of greater than 20V (I would pick a minimum of 30V to be on the safe side) and an IDS of at least 5A (a 10A FET should be well good enough).
The chip pulls the FET gate to 0V, so the FET needs to have a VGS threshold of Vin (min) (20V in the case above). RDSON should not matter. They are all low these days.
YOu are not switching at speed so other factors such as input capacitance and QG should not matter.
The datasheet is extremely well written, as are all LTC datasheets.