CREATE TABLE table_name_30 (surface VARCHAR, outcome VARCHAR, score VARCHAR)

On what Surface was the match with a Score of 6 4, 6 3 and Runner-up Outcome played?
SELECT surface FROM table_name_30 WHERE outcome = "runner-up" AND score = "6–4, 6–3"
SELECT "surface" FROM "table_name_30" WHERE "6–4, 6–3" = "score" AND "outcome" = "runner-up"