While publicity about the Reagan budget cuts has rightfully focused on the big-dollar items, the smaller ones show just how widespread is the range of government activities -- and changes that are taking place. Where do you find this information? In the Register, of course, where on March 23 (pages 18174 to 18306) are details of 81 proposals to rescind (governmentese for withdrawing) $11.1 billion in already approved fiscal 1981 funds. Some examples:

The United States has run into trouble with the Bolivian government over its drug control program since some officials in that country allegedly were caught trafficking. As a result, the joint government narcotics control plan is being halted and $3.1 million can be saved.

Improved availability of food in Kampuchea (Cambodia) and a decline in the number of Soviet refugees being resettled in Israel permits the State Department to cut $22.5 million from its migration and refugee account.

That dropoff in Soviet Jewish emigres is also reflected in part of the $25.1 million the Department of Health and Human Services wants to slice off its refugee assistance. Since Indonesian refugees along with the Soviet emigres are down, admission to the United States during the first quarter of fiscal 1981 overall were 40 percent lower than what the department had expected.

Reduced activity for arms control negotiations is permitting the administration to cut $1.5 million from the Arms Control and Disarmament Agency budget.

Also being cut:

$24.7 million that since 1979 has been available through the Department of Transportation to test "high-speed, water-borne transportation equipment" around New York City to determine feasibility for a new mass transit service.

$1.9 million in on-line computer terminals for each of the nation's 400 area Selective Service system offices.