It's the size of a big-city telephone directory and, down in the fine print, in the small letters and numbers, you find the real grist of federal budget-making--a far cry from those sweeping presidential messages.

For example, the costly dimensions of the recession that the administration says has just about ended show up in the appendix to President Reagan's fiscal 1984 budget, which went to Congress yesterday.

And, as it turns out, Uncle Sugar gets stuck with the tab. No surprise there. But even before getting to next fiscal year, which doesn't begin until Oct. 1, the appendix shows that the president still is wrestling with the here and now of fiscal 1983.

For starters, note the Small Business Administration. It wants an extra $178.6 million to carry it through the rest of fiscal 1983 to make good on defaulted loans from previous years, loans to little entrepreneurs who went belly up.

Or consider the Federal Aviation Administration. As a guarantor of loans, the agency has to produce $45 million extra to bail out three airlines, not named in the budget, that failed to pay either principal or interest on aircraft purchases.

Bankruptcies are running high, which everyone knows, but now the federal bankruptcy court system needs an extra $2 million this year just to cover additional postage costs for mailing bankruptcy notices.

Those might be small potatoes for the big-picture boys, but there are some Idaho bakers in there as well. To wit:

Before it even gets to fiscal 1984, the Department of Labor wants Congress to fork over another $5 billion to keep the unemployment trust fund afloat, "to make the benefit payments required by law."

At the Department of Agriculture, the food and nutrition people need $1.2 billion more for food stamps because unemployment has pushed demand for benefits right off the charts.

Just down the hall at the Commodity Credit Corp., $5.7 billion is needed to cover unexpected costs of price-support loans to farmers who are turning over grain, rice and cotton to the government in record amounts.

There is, nonetheless, a silver lining in Reagan's budget appendix. Not everything is going up in the fiscal 1983 revisions. The cost of the summer youth program actually will be going down by $85 million, if one of the president's new anti-recession plans gets off the ground.

Remember the president's idea of a lower minimum wage for teen-agers? Some pecksniff at the Department of Labor has figured that the program can obtain jobs for the same number of youths but that they won't have to be paid as much.

Of course, the budget-makers' crystal ball isn't omniscient. Who, for example, back in early 1982 would have guessed that firebugs, air controllers, drug tamperers and sick coal miners would be costing the Treasury extra money this year?

Nobody, and now there's a price to pay. The Merit Systems Protection Board needs an extra $1 million to process appeals by air controllers fired by Reagan over money demands two years ago. The Food and Drug Administration wants $5 million more to cover extra costs of monitoring urgent recalls of drugs such as Tylenol after the tainted capsules were found last year.

There's also additional evidence that more than ever, we need Smokey the Bear. The firefighting budget for this year has gone up in smoke. The U.S. Forest Service needs $59 million more; the Interior Department's Bureau of Land Management has put in for $45 million, and its Bureau of Indian Affairs, saying its territory is threatened by wildfires, needs an added $14 million.

The administration's supplemental budget request also calls for an additional $54 million to cover costs of federal black-lung benefits, monthly payments to coal miners disabled by breathing coal dust.

The president, who got his start in radio, hasn't turned his back on that medium. He's asking for about $70 million more in his fiscal 1983 supplemental to carry the Big Story to overseas listeners.

The big-ticket item is an additional $21 million for Radio Free Europe and Radio Liberty, which beam news and features behind the Iron Curtain. Despite the static in Congress about Reagan's proposed Radio Marti, aimed at Cuba, the president is pushing for $8.5 million to get it on the air.

Another of the president's pets, the U.S. Information Agency, is asking for an additional $42 million. Of that, $20 million is to be doled out to organizations worldwide that work to promote "democratic institutions." The rest is for improving the Voice of America, including reactivating a relay station in California.

After the USIA wins those new friends, it will have to entertain them. The budget for fiscal 1984 calls for a big increase in the agency's entertainment kitties at home and abroad. The home kitty would year will meow to the tune of $50,000, five times what it has now. The overseas kitty would positively howl, increasing $115,000 from today's $500,000.

While most other government agencies are being frozen, the USIA has cracked the budgetary ice. Its basic program would rise a whopping 20 percent next year to $634 million. Part of that would cover U.S. participation in the 1985 Tsukuba, Japan, and 1986 Vancouver expositions.

Another $48 million is sought to spread USIA antennae to Sri Lanka, Botswana and unidentified "additional sites in the Middle East, Far East, western Mediterranean and Europe." Everywhere, in other words.

The Yankee dollar would be headed overseas in other ways, too. Under the Panama Canal treaty that he opposed as a candidate, Reagan asked for $375,000 to pay Panama.

That represents the profit from canal operations that the United States, under the agreement, must turn over. The budget says the president has agreed by diplomatic promissory note to pay by April 30.

The Reagan budget includes other categories also intended to influence foreign thinking.

One is called arms sales, which for fiscal 1984 would increase credits by 28 percent to $5.2 billion to provide weapons to friendly countries.

But even before year's end, the president wants to add $525 million to the current budget, including $100 million for rebuilding the Lebanese armed forces and $1 million for military training in the United States. Lebanon also is in line this year for $100 million in economic support.

While the United States has curbed shipments of agricultural goods to credit-shy Poland, American help is on the way to produce home-grown goodies. Reagan's supplemental budget seeks release of an additional $3 million in foreign currency to "implement agriculture research" in Poland, among other places.

The administration's full-court press against global drug trafficking would be expanded next year by almost 50 percent. It wants $43 million to pay other countries to crack down on production and processing of narcotics and psychotropics, as the budget puts it.

On the home front, the press is even more determined. A dozen new regional antidrug task forces would be financed with $105 million and of that, $9.6 million, according to the budget, will be for "undercover operations"--a category rarely mentioned in past budgets. Such new candor also extends to the FBI, but the bureau would receive only $1 million for undercover work.

Of note is a contrast between proposed spending for the Drug Enforcement Administration and the General Services Administration. The DEA is allowed $1.7 million to pay drug snitches. The GSA would receive $10,000 to pay for squealing about fraud in government.

Terrorism is gone from the front pages, but the administration hasn't forgotten it.

The Army, which has had its scrapes with political knee-cappers in Europe and elsewhere, wants to buy 30 specially equipped armored vehicles to protect personnel. The brass also want permission to pay more for each vehicle, up to $125,000 apiece.

The State Department also is getting into the act, seeking $5 million to train foreign law-enforcement authorities in antiterrorism techniques. State also wants $6 million to pay state and local governments and rent-a-cop outfits to protect foreign diplomats in the United States.

It's clearly a growth industry, because the Secret Service has a similar program. This one would cost $3.5 million, providing similar payments for the protection of similar foreign diplomats.

The hundreds of pages of the 1984 budget appendix, the real road map of government spending for the coming months, are replete with fiscal nuts and bolts. Pick a page, find a nut or a bolt.

* Bolt: $50 million in the Department of Defense budget to pay for military "logistical support and personnel services" for the 1984 Summer Olympic Games in Los Angeles. Legislation explaining this is to be proposed.

* Nut: $220 million for "a special classified program" at the Pentagon. Don't dare ask for details.

* Bolt: Savings at Agriculture where they're cutting $2 million from the Mediterranean fruit fly protection program and $893,000 from the war against the pink bollworm.

* Nut: Congress, bless its non-recessionary heart, is doing all it can to keep the postman busy. The House and Senate want $25 million in addition to the $55 million already received to cover "official mail costs." Next year, so as not to be caught short in an election season, the two chambers are asking for $107 million.