IN THE BUSINESS . . . Porten Sullivan Corp., a prominent residential builder in this area, has formed a Florida subsidiary and plans to enter that market this year. Heading the new branch, based in West Palm Beach, will be Chris Brown, formerly an officer in the Florida division of Campeau Corp., a Canadian development firm. Joining it as a vice president will be Stephen Porten, an architect and an officer with Porten Sullivan's Washington operations. The company plans to start acquiring property immediately and to begin multifamily and detached-housing projects this year, according to Herman Porten, Porten Sullivan's chairman . . . Trustees of the Reviere Realty Trust have voted to change the trust's name and move it to Jackson, Miss. If its stockholders approve, the firm will enter into a cost-sharing arrangement with Eastover Corp. and several affiliates and become known as the EastPark Realty Trust. David H. Hoster II will continue as president and will become an officer of Eastover. Joseph D. Reviere, the trust's founder and chairman, has announced his resignation . . . Ground was broken last week for the first of four planned 10-story buildings at The Greens at Leisure World. The introduction of mid-rises is a change for Leisure World, which has been primarily duplexes, town houses and low-rise buildings since its beginning in 1964. The new buildings will contain 250 condo units each . . . Danac Real Estate Development Corp. expects to begin construction soon on its newest office park, on Shady Grove Road at the east corner of Montgomery County's medical center complex. Four buildings are planned for the 13-acre office park, totaling more than 220,000 square feet of space.

PERSONNEL FILE . . . The Mortgage Bankers Association of America has promoted Schuyler E. Schell to the post of director, government agency relations . . . B. F. Saul Co. has named Jonathan C. Swindle vice president, finance, legal and administration. He comes to Saul from Orkand Corp. The firm also announces the appointment of Arthur E. O'Donnell as vice president for construction and C. William Royan as vice president for shopping center operations . . . John W. Renner has been elected executive vice president for commercial investments of Rouse Real Estate Finance, the mortgage banking subsidiary of The Rouse Co. . . . Merrill Lynch Realty/Chris Coile Inc. has named Butch Kline vice president and branch manager of the firm's Bethesda/Chevy Chase office.

ON THE MOVE . . . Educational Testing Service has moved its Washington office from 1800 Massachusetts Ave NW to International Square, 1825 I St. NW, where it will occupy 5,700 square feet beginning Aug. 1. . The Fred Ezra Co. represented ETS in the deal . . . Corby-Lynn Real Estate Co. Inc. was awarded the management contract for 1518 K St. NW. The Patterson family recently sold the building to 1518 K Street Limited Partnership.