A B767-300 Captain that after a wake vortex encounter shortly after takeoff the 'Rudder Ratio' light came on; limiting the crosswind on landing to 15 KTS.

Narrative

Just after liftoff we flew through what felt like wake turbulence with left and right movement. The 'Rudder Ratio' light came on. We did the checklist when we were climbing at a safe altitude. It said not to make any large rudder inputs when above 160 KTS. It also said not to land in a crosswind over 15 KTS. I checked the forecast and it was for very light wind. ATIS said that the wind was variable at 3 KTS. On final approach when we switched to tower he told us the wind was 16 knots direct crosswind. We told him that our max cross wind was 15 KTS. The wind then increased to 19 KTS. The tower had us fly over the airport. We asked for the east runway. He informed us that we would have to hold for about 45 mintues to get it. Since we had only about a little over an hour of fuel remaining; that did not sound good. He then said the wind had changed and was now staying at about 9 KTS. So when landed on the south runway. The wind stayed at 9 KTS. This is the second time I have had the rudder ratio fail. It could be bad situation if there is no runway near by that can be within limits!