Susan King has been selected chairwoman of the Consumer Product Safety Commission, according to informed sources.

Approval of the appointment still awaits the signature of President Carter, who is expected to meet personally with King in the next few days.

S. John Byington, the current chairman has resigned effective June 30.

Byington, a Republican, said yesterday he would be joining the Detroit law firm of Bushnell, Gage and Reizen. He will be a full partner in the firm, and will open its Washington office. Byington said his legal aide at the CPSC, Mary Martin McNamara, would be joining him at his new firm.

Although it is expected that Byington would be working in the regulatory area, he is forbidden by law from handling any CPSC business for one year.

Byinton, was a controversial leader of the CPSC. The 5 year-old agency was in a state of chaos when he took over more than two years ago. Although he is credited with making significant progress in terms of managerial reform, he was heavily criticized for alleged violation of civil service rules while "cleaning house" at the agency.

In addition, the agency has been criticized continually by Congress and consumer groups for being moribound and unproductive. Byington's resignation, announced early this year, was considered a major factor in the reauthorization of the CPSC for another three years.Morale at the commission reportedly has been on the upswing in recent months.

King, a democrat, was nominated to the commission in January by President Carter, and was elected its Vice Chairman on June 1.

The 38-year-old King has earned the respect of CPSC staffers and consumer groups during the past six months.

A native of Sioux City, Iowa, she is a Phi Betta Kappa political science graduate of Duke University.She has extensive experience in dealing with consumer issues both in the public interest sector and as a Congressional aide. Before coming to the CPSC, she was a staffer at the Federal Electrion Commission.

Reached by telephone, King would not comment on the possible appointment. "I haven't been told anything," she said, adding that there was nothing to say until "the White House announces something."

But consumer leaders were clearly pleased yesterday with the apparent selection of King, although it is likely they would have been equally pleased had the choice been either David Pittle or Edith Barksdale Sloan, the remaining two Democratic members of the commission who were also under consideration.

"Susan is very dynamic," said Mark Green of Congress Watch, a Ralph Nader group. "She conveys a kind of take-charge personna, and she'll be aggressive and open-minded."

Sen. Wendall Ford (D-Ky.), who heads the Senate Commerce Committee, which has oversight authority over the OPSC, and said "if she has been selected, I see no reason why I shouldn't have a good working relationship with her."

Sources said the White House interviewed the three Democratic members before deciding. King was seen as a favorite, they said, becase she was the only one who Carter appointed without significant political pressure.

Pittle was reappointed by Carter with considerable pressure from consumer groups who saw him as the leading consumer voice on the then-predominantly Republican commission. Sloan, a black, was heavily lobbied by minority groups. "King was really Carter's only discretionary choice," one source said.

Her term would expire in October, 1984.