Fifteen No. 1 draft choices have signed with National Football League clubs, as have about half of the rest of 334 college players picked May 2-3.

If those who haven't signed are not given specified minimum offers by today they will become free agents with no strings attached.

Minimum offers are designed to establish a sort of "floor" for negotiations and to protect a club's rights to deal with its rookies.

A club can:

Offer a one-year contract with an option year at a salary of $20,000.

Offer a two-year contract of $25,000 for the first year, $35,000 for the second. An option year is not mandatory.

Offer a three-year contract of $30,000 for the first year, $40,000 for the second and $50,000 for the third. No option year is mandatory.

Offer a four-year contract of $35,000 for the first year, $45,000 for the second, $55,000 for the third, $65,000 for the fourth. No option year is mandatory.

There is a stipulation that half of the multiyear contract be guaranteed whether the rookie plays or not.

And, a player is not obligated to sign any of the four offers. But he has to ist out a year.

The he could be drafted again in 1979, by any team except by the club that selected him for 1978.

If he reached no agreement after being drafted in 1979 he again would become a free agent.

Kicker Tom Skladany of Ohio State did not accept an offer from the Cleveland Browns after they drafted him in 1977. He sat out last season and would have been eligible to be drafted in 1978 had he not signed with the Detroit Lions, who obtained the rights to negotiate with him from the Browns.

Top draft choices who have signed contracts are Earl Campbell of Texas, by Houston; Art Still of Kentucky, by Kansas City; Wes Chandler of Florida, by New Orleans; Chris Ward of Ohio State, by the New York Jets; Terry MIller of Oklahoma State, by Buffalo; Ross Browner of Notre Dame, by Cincinnati; Keith Simpson of Memphis State, by Seattle; Clay Matthews of Southern California, by Cleveland.

And Mike Kenn of Michigan, by Atlant; Blair Bush of Washington U., by Cincinnati; Elvis Peacock of Oklahoma, by Los Angeles; Randy Holloway of Pittsburgh, by Minnesota; Ozzie Newsome of Alabama, by Cleveland; Dan Bunz of Cal State-Long Beach, by San Francisco, and Don latimer of Michigan State, by Denver.

Unsigned are James Lofton of Stanford, drafted by Green Bay; Ken MacAfee of Notre Dame, by San Francisco; Gordon King of Stanford, by the New York Giants; Luther Bradley of Notre Dame, by Detroit; John Jefferson of Arizona State, by San Diego; Steve Little of Arkansas, by St. Louis; Doug Williams of Grambling, by Tampa Bay; Bob Cryder of Alabama, by New England; Ken Greene of Washington State, by St. Louis; Ron Johnson of Eastern Michigan, by Pittsburgh; reese McCall of Auburn, by Baltimore; John Anderson of Michigan, by Green Bay; and Larry Bethea of Michigan State, by Dallas.