Among all the words to be said in memoriam today, a few ought to be reserved for those whose judgment calls led to a double debacle for ABC and the White House yesterday. Specifically, two wreaths might be laid on the credibilities of those who:

(a) Decided that this year's ABC coverage of the Indianapolis 500 should be live for the first time ever and with no backup insurance against a washout, and

(b) Advised President and Mrs. Reagan to walk out in front of live cameras for their part in the Hands Across America project.

The race was rained out, but it took nearly six hours of air time for that to come about. That left ABC anchor Jim McKay and his minions with wide-open spaces to fill and gaping chasms to plug. They did it with aimless chatter and religiously hopeful weather forecasts. "It continues to brighten a bit," said McKay optimistically. "The drying process continues."

Yes, when it comes to dynamic television, there's nothing like watching a race track dry. And this was in the fifth hour of ABC's marathon nonevent coverage.

At around 3, ABC News mercifully intervened with a cutaway report on the Hands Across America demonstration, whose organizers had designed it to raise money for, and raise consciousness about, hunger in America. ABC's coverage of participants milling about in California, the District and New York City was as poorly directed and clumsily photographed as any live network coverage of anything in recent memory.

A camera would pan down the Capitol dome to the Mall and then the director would cut suddenly to a shot of teaming masses in Long Beach. Nowhere did you get a sense of a long-linked line of participants, the whole point of the event. Shots of the Mall looked like a typical Sunday in May.

As sorry as one may have felt for Jim McKay as he struggled gamely to sustain the illusion that something was actually happening in Indianapolis, other than a downpour, one had to feel sorrier still for that other veteran broadcaster, Ronald Reagan, who had been persuaded, perhaps by daughter Maureen, to come out of the White House and take part in the Hands Across America business.

In static and embarrassing live shots from in front of the White House, Reagan, looking discomfortingly gaunt and slightly bewildered, in a blue pullover shirt and blue pants, stood between children and clutched their hands for long, long minutes while supposed soul-stirrers like "We Are the World" and "Hands Across America" were piped in from loudspeakers. Nancy Reagan, in a bright red skirt, was a little farther down the line, to the president's right.

Daughter Maureen, meanwhile, was off to his left, between two more children, and as she bounced merrily and sang along enthusiastically, she looked like a new zaftig hostess of "Romper Room." To the casual viewer she seemed to be a prime suspect in giving the president bad media advice.

Organizers of Hands Across America should have realized in advance that the concept of a coast-to-coast human chain, however imposing to imagine, cannot adequately be captured by television cameras. What came across on the air was just isolated groups of people who might as well have been patrons at a rock concert. And if the project wasn't going to look good on television, which can connect with more consciousnesses than you can shake a stick at, then its usefulness would be limited. Only ABC gave extensive live coverage to the event at midday, and the fact that it was so unimaginative detracted from whatever impact it might have had on television.

President Reagan apparently had printed lyrics to the would-be anthems in his hand and would occasionally try to sing along with the recorded music. Unfortunately it only added to the pervasive emptiness of the whole gesture, and further compromised his presidentiality. That the president had been perceived as doing penance for an allegedly insensitive remark about hunger that he made last week didn't do any wonders for his dignity, either.

The result was the kind of flat, awkward footage that is bound to turn up mischievously redubbed on HBO's hilarious satire program "Not Necessarily the News."

Soon ABC went back to Indianapolis for Not Necessarily the Race. By this time, it had become one of the certifiable disasters in television history. It could only get better by getting worse. Tom Binford, chief steward of the track, could be heard to declare, of the possibility that the race might actually take place, "There's a chance, there's a chance." The ghost was given up in about another hour. ABC Sports President Dennis Swanson later told reporters that another attempt will be made to air the postponed race today, but that if there's another rain-out ABC will probably throw in the old towel and forget it.

Next year, it seems awfully likely ABC will revert to its own tradition and show the race via tape delay or at least have an alternative to a Jim McKay talkathon at hand.

While McKay talked, cameras panned the stands to capture fans grilling hamburgers and VIPs in deep powwow. In desperation, McKay offered highlights from the 1982 Indy 500, attempting even to generate suspense about its outcome. What ABC's financial losses will be (in make-goods to advertisers who bought commercial time) remains to be calculated.

A call to the ABC Sports desk in New York was answered by a young man who refused to relay inquiries to ABC spokesmen and declined to say how many viewers had called in to complain about the rain-out. He was asked for his name. "I'm not allowed to give that out," he said.