"I know who Mrs. Bush is," squealed 5-year-old Dominic Bradley, his eyes popping with pride. "She's, she's President Carter.

"How come you don't know that? You look pretty big to me."

One silly question dismissed, Dominic turned to finish what he had started. Tugging at Barbara Bush's hemline, Dominic prodded, "Mrs. Bush, Mrs. Bush, can you write my name in my book?"

President Carter or not, Barbara Bush was definitely an Important Person at an Important Event last week for youngsters at Cameron Valley Elementary School in Fairfax County. It was a Reading Is Fun-damental book distribution day and about 475 students crushed the front steps to welcome Bush on her first day as a new board member of the national reading program, better known as RIF. Under RIF guidelines, each student was allowed to select and keep one book.

But the main attraction for the youngsters was Barbara Bush.

"Mrs. Bush, I like your hair," gushed one youngster as she pressed a copy of "Little Women" against her lace-collared blouse. "And, you know what? I really like your car."

"Well, thank you very much. You know a lot of people tell me they don't like my hair. And, I like my car, too, but" Bush laughed, leaning toward the young lady and other younsters clustered breathlessly around her, "it really belongs to you and you and you."

The young ladies beamed, rushing off in whispers, "She's sooooo nice."

Book signing was not Bush's only aim. She was there, she said, to spread the RIF message.

"RIF is a proven success," Bush said, noting that nearly 37 million books have been distributed since the program began in the District of Columbia nearly 15 years ago. RIF, a private, nonprofit organization supported largely by foundation grants and private donations, helps community groups organize book giveaways for children. RIF encourages children to read by letting them choose a free book to take home.

RIF has programs in almost 12,000 places in all 50 states, Puerto Rico, the Virgin Islands and Guam. In Northern Virginia, RIF officials said that students will choose more than 45,000 books this year.

"Nearly every single door is closed to someone if they can't read and there are some 23 million functionally illiterate people in this country," Bush said. "RIF can help solve some of those problems."

When asked if the administration's proposed cutbacks would affect the RIF program, Bush at first side-stepped the question, noting quickly that RIF is largely run by volunteers, more than 115,000 in the nation.

Since 1975, federal funds have paid for about 75 percent of books distributed under the program, and Bush was asked if budget cutters would give RIF the same hands-off policy as Nancy Reagan's pet project -- Foster Grandparents.

"RIF has some very good spokesman who will lobby hard for the program, but Barbara Bush will not be one of them," Bush stated emphatically. "I have never discussed RIF's funding with George."

A RIF spokesman said the program could fall under one of the two consolidated block grant programs, where Reagan has proposed funding cutbacks. Under that plan, it would be up to state governments to determine how the block grants would be allocated.

Before whisking back across the river to Washington, Bush stopped to chat with one young lady who had followed Bush persistently throughout the morning.

"Mrs. Bush, you know what?" the child finally volunteered. "My mom and dad voted for President Reagan."

"Well, thank you very much," Bush replied. "Thanks to you I have a house. A very nice house."