HowardStringer, who has been president of CBS News since October 1986, finally signed his contract with CBS Wednesday. The two-year pact, retroactive to October, will expire just one week before the November elections in 1988, but Stringer said yesterday this was only "a coincidence" and had no significance.

The agreement was sealed with a handshake six weeks ago, Stringer said, and delays were caused only by such events as his trip to the Soviet Union, and not by disagreements over money. He declined to comment on his salary, except that when asked if it were $500,000 or more, he said, "Don't be ridiculous."

Sources said the raise Stringer gets with the new contract will put him closer to the estimated $300,000 earned annually by NBC News President Lawrence Grossman. It is widely believed that ABC News President Roone Arledge is in the $1 million range because he holds the title "group president, ABC News and ABC Sports."

CBS reportedly wanted Stringer to sign for four years but he preferred two.

Asked if he were worried about seemingly declining ratings for "The CBS Evening News With Dan Rather," currently in third place, Stringer, once executive producer of the program, said the ratings services are in such a state of flux that the figures are inconclusive. Nielsen is phasing out its old diary system and phasing in the new and complicated "people meters."

By diary data, Stringer said, the Rather program actually won the May ratings sweeps by a 1-million-household margin. -- Tom Shales