MARBLEHEAD-Selectmen have appointed another new member to the Conservation Commission.Informed last week that commission member Betsy Rickards has submitted her resignation, board members lost no time turning to the list of applicants they interviewed last month.Don Tritschler, a member of the Massachusetts Recycling Committee, was one of four candidates interviewed Jan. 23. On a unanimous vote, 4-0, selectmen named him to the committee last week.His term will end in 2010.They will join Chairman Walter Haug and veterans Craig Smith and Fred Sullivan on a seven-member board that has added four new members in the past three weeks.Architect Ken Fischer will serve until 2010; health care professional Deb Payson will serve until 2009; lawyer Brian LeClair will serve until this spring. All three were appointed Jan. 23.Selectmen said that small business owner Jacqueline Rosenthal, who also interviewed for a seat on the Conservation Commission, could be considered for a seat on another town committee.