Max size of RC is 4, period, and that is in both city and stronghold. Townsland is 3. Everything else is 2.
So that is the fact.. Thank for answering my question. But, anyone can tell me how must i pay to enlarge Rc to level 2,3 and 4.. I has enlarge one cavarly rc in city and cost me 300 gold (just enlarge to level 2)..