Floretta D. McKenzie took over as superintendent of the District's public schools yesterday with the firm declaration that she intends to "work right beside" her staff, and will supervise directly many of the tasks that previously had been left to individual department heads.

In marked contrast to the leadership style of her predecessor, Vincent E. Reed, who generally gives deputies broad directives and left them to work out the details, McKenzie said she sees her role as "play-coach. . . I'll be directing the activities of my staff but I'll also be working alongside them. . . . There are specific offices I intend to directly supervise."

The management services division, which handles budget and finance matters, and several smaller divisions -- including labor relations, legal services and communications -- now answer directly to the superintendent. Associate superintendents are directly responsible for other key areas, such as curriculum and instruction, program development, student services and education for the handicapped. McKenzie indicated changes would be made in this table of organization.

Although McKenzie declined yesterday to say which divisions she plans to directly supervise, one source who has worked with her closely said she probably would assume more direct control over curriculum and instruction -- areas that Reed generally left to experts on his staff.

McKenzie said that she would announce her reorganization plans within a month.

"I know Floretta and she won't miss a trick," said one longtime administrator who worked with McKenzie when she was acting District superintendent in 1974. "What she'll probably do is poke her head in on divisions heads regularly to see where they are and what they're doing."

"She's going to be strictly business," said Roland Otey, the system's chief accountant, who attended McKenzie's first staff meeting yesterday, along with other key staff members.

Overall, it was a day of back-to-back meetings, of seeing old colleagues and meeting new ones, that began at 7:50 a.m.

She gathered at 9 a.m. with the system's top adminstrators, and announced at that time that Andrew E. Jenkins, currently the associate superintendent for education programs, is her choice for deputy superintendent. Jenkins, 44, was one of the finalists whom the school board considered for the superintendent's job.

McKenzie then met with the system's budget and finance directors. One of her first acts, she said, will be to determine where the budget might need cutting to ward off an anticipated deficit of about $9 million. The system also stands to lose as much as $10 million in federal funds, school officials have said.

The school board has already approved a plan to furlough all school employes for a number of days before school opens in September to save nearly $1 million a day. It has not been decided how many paydays employes will lose, but McKenzie said she will decide within the next two weeks such details.

But also met yesterday with planners of the city's new academic high school and said she expects the college preparatory school to open as scheduled in September.

Former acting superintendent James T. Guines, who returns to his old post of associate superintendent in the area of instruction and curriculum, was with McKenzie most of the day. She praised him for his "tremendous support and cooperation."