"Kissinger in Retrospect" on Channel 26, at 8 o'clock tonight, is a devastating examination of the personality and the record of the personality and the record of the most powerful Secretary of State this nation has had in this century.

It is devastating because it is fair. That is not a contradiction. Kissinger has enjoyed the reputation of being a diplomatic Merlin because, with few exceptions, his press coverage, especially by television, has been so adulatory.

That has been unfair not just to the public, but to Kissinger as well, for he is a man of vanity and insecurity, who both fed upon and acted upon the rave reviews he received from journalists in Washington and elsewhere.

Though the 90-minute documentary had not been completed last night - Kissinger's speech at the National Press Club yesterday was still being edited for inclusion - executive producer Wallace Westfeldt had enough in hand to demonstrate that this examination would be quite different from the usual puff pieces we have come to expect on the commercial networks on this Secretary of State.

Kissinger is not interviewed. Martin Agronsky, who hosts the program, and syndicated columnist Stanley Karnow, who did much of the reporting, invited Kissinger to appear. He declined.

Even without Kissinger's participation, the journalism of this documentary is thorough. It starts with a reconstruction of his youth in Nazi Germany> his return there as part of the olccupation and notes an early instinct of Kissinger's part to depend on the kindness of patrons for advancement in the world of international affairs.

From there it moves to the most fascinating part of the program - how Kissinger understood, as a Harvard professor without a political constituency, how he would use the press as his constituency of power.

As Leslie Gelb, diplomatic correspondent of The New York Times, indicates in an interview with Iarnow, Kissinger understood that "politics is theater." There follow still pictures of the famous people Kissinger associated himself with in his effort to first attract and then monopolize the attention of journalist: The Pope, Johnny Bench, Hoe Namath, Jill St. John and Shirley MacLanie.

Gelb goes on to note that in a city where the press is mainly interested in power, the most important thing to a reporter is information. This theme is expanded by Gelb as to how Kissinger used the dispensing of information to columnists and reporters as a way of enhacing and broadening his power.

Morton Helprin and William Watts, two early Kissinger aides who resigned, pick up this theme of information to recall how Kissinger's power with Nixon was based on his understanding that Nixon placed a high value on those that could supply him, quickly and succinctly, with information.

Halperin notes that when William Rogers became Scretary of State and was presented with the huge briefing books assembled by his staff, he allegedly siad: "I'm not going into all that detail." Says Halperin: "From that moment, Rogers was finished."

There are other segments that deal with Kissinger's policies on Vietnam, the Soviet Union, China, the Middle East and Africa. Kissinger is given pluses and minutes by academic critics and is ably defended by two aides, Helmut Sonnenfeldt and Winston Lord.

Kissinger will probably not like this examination of his personality and record. (His office was trying to get the transcript of the program late yesterday afternoon.) But it stands as a healthy antidote to the adulation that has surrounded his man for the past eight years, and the remaining one-sided praise that no doubt will be heard from his admirers during his remaining 10 days in office.