There is no office of Vietnam embassy in Saint Kitts and Nevis up to now.
To request for legalization/verification of Vietnamese citizenship, etc., you have to contact the consulate or embassy of Vietnam in the nearest country to get detailed guidelines. You can find Saint Kitts and Nevis’s nearby embassy of Vietnam here.
To request for a Vietnamese visa, consider two options below:
Vietnam visa on arrival is also known as visa at the airport and highly recommended for air travelers to Vietnam from Saint Kitts and Nevis or any other country since it requires no contact with the Vietnam embassy for application). See how Vietnam VOA works.