WASHINGTON (AP) _ A White House spokesman said today there would be no impropriety if President Reagan names the wife of Sen. William V. Roth Jr., R-Del., as a federal judge.

White House deputy press secretary Robert Sims refused, however, to confirm that Jane Richards Roth will be nominated soon to the U.S. District Court in Wilmington.

''We haven't announced that,'' Sims said. ''I couldn't say what's in the process until we come to the end of the process.''

Sims noted that White House counsel Fred Fielding has interviewed Mrs. Roth. ''At this point, I see no problem (as to) the question of propriety,'' Sims said.

The Washington Post said the senator had recommended Mrs. Roth's name to then-Attorney General William French Smith after she had unsuccessfully promoted herself with the Justice Department for a seat on the 3rd U.S. Circuit Court of Appeals.

Roth acknowledged that it is ''somewhat awkward'' for him to be recommending his wife, the newspaper added. However, it quoted him as saying, ''Whenever anyone asks, I say I strongly support her.''

Mrs. Roth, 49, a Harvard Law School graduate, is a partner in a firm founded by her grandfather.