Former national security adviser Robert C. McFarlane and the former U.S. ambassador to Canada supported in their testimony yesterday the charges that former White House aide Michael K. Deaver lied to a congressional subcommittee and a federal grand jury that investigated his lobbying activities.

McFarlane supported the prosecution's contention that Deaver had contacted him about a tax benefit for Puerto Rico, one of his lobbying clients, and worked for resolution of the acid rain issue with Canada, another client. Paul H. Robinson Jr., the former diplomat, backed the contention that Deaver was present during a Dec. 27, 1984, discussion of the acid rain issue with Canadian officials.

But neither McFarlane nor Robinson were as specific in their memories of Deaver's alleged lobbying efforts as prosecutors had indicated they would be.

McFarlane said Deaver had called him at the White House and mentioned that he was working on a federal tax benefit for Puerto Rico. McFarlane said he later canceled a meeting with Deaver after White House lawyers had warned the staff about meeting with ex-staffers.

But McFarlane said Deaver's mention of the tax issue was brief and that Deaver's support for resolution of a dispute over acid rain pollution with Canada was also sketchy. "Mr. Deaver expressed the hope that we could avoid a public disagreement" over the issue at an upcoming summit with the Canadian prime minister, McFarlane said.

Deaver, the former White House deputy chief of staff, is charged with five counts of lying to the congressional panel and the grand jury about his involvement in the acid rain issue and the extent of his contacts with top Reagan administration officials after he left the government May 10, 1985. Deaver, a longtime confidant of President Reagan, has contended that his statements that he did not recall meetings were truthful and that his alcoholism and health problems had affected his memory.

Yesterday, the ninth day of the prosecution's case, saw McFarlane buttress some prosecution allegations and reject others. He said that while Deaver supported the appointment of special envoys to work out the pollution issue with Canada, Deaver told him at one point that any of three candidates for the job would "be okay by me."

Special prosecutor Whitney North Seymour Jr. has alleged that Deaver championed the nomination of former transportation secretary Drew Lewis for the position.

Deaver has testified that the earliest he can recall participating in a discussion of acid rain was in March 1985. Robinson, the former ambassador, testified that Deaver was present at discussions of the issue Dec. 17, 1984, during planning for the so-called Shamrock Summit between Reagan and Canadian Prime Minister Brian Mulroney to be held three months later in Quebec City.

Robinson recalled riding to the airport in an armored gray Buick, and Canadian Ambassador to the United States Allan Gotlieb launching into a five-minute lecture on the need for action on acid rain.

Gotlieb, who has invoked diplomatic immunity and declined to testify at the trial, said "something has to come out on acid rain for the summit to be successful," Robinson said. Deaver "almost distractedly . . . offhandedly" said to a U.S. official, "See what we can do about this, but try not to bureaucratize this," Robinson said.

The former ambassador, who described himself as a fund-raiser for Reagan's 1980 campaign, said on cross-examination that Deaver never specifically advocated the appointment of a special envoy during the discussion. Robinson said he clearly remembered the discussion because Gotlieb had startled him by saying his government had done "many foolish things" and described two policies, which he had strongly defended previously, as "stupid."

Deaver's lawyers spent most of the morning attempting to play down the significance of a National Security Council routing slip on which the council's executive secretary had written: "Deaver is still keen on special representative."

The note, written in mid-February 1985 by Robert Kimmitt, was described repeatedly by defense lawyer Stephen L. Braga as "just a little tiny note."

Kimmitt said he had based the notation on a question Deaver had asked at a long-range planning meeting, rather than on any strong advocacy of the appointment of envoys. But in later questioning, Kimmitt told prosecutor Marc J. Gottridge that he placed the comment on the slip because he believed it showed "where Mr. Deaver stood" and it was "one key fact" that was not mentioned in the accompanying documents on acid rain that were being forwarded to McFarlane and his deputy, Rear Adm. John M. Poindexter.