RCA Corp.'s profits fell 27 percent in the final quarter of 1981 and plunged 83 percent for all of last year, and its chairman said the company's dividend to stockholders may be cut.

Meanwhile, Bethlehem Steel Corp., the nation's second-largest steel producer, said that earnings fell 44 percent in the fourth quarter but rose 74 percent for all of 1981.

RCA blamed rising interest rates, poor ratings for its NBC-TV subsidiary, write-offs for television programs that will not be rerun and high costs for starting up its VideoDisc home entertainment venture for its decline.

RCA Chairman Thornton F. Bradshaw said that when the company's directors meet in March, they will consider "the desirability of continuing the present level of dividend payout . . . in light of conditions existing at that time." RCA currently pays shareholders a quarterly dividend of 45 cents for each share of common stock.

Analyst Charles Ryan, who keeps track of RCA for the investment firm of Merrill Lynch, Pierce, Fenner & Smith Inc., said the financial results were about as expected and that the encouraging news was that "things have not deteriorated" further.

RCA said fourth-quarter earnings fell to $57.8 million (54 cents a share) on revenue of $2.11 billion from $79.1 million (82 cents) on revenue of $2.09 billion in the same 1980 period.

Earnings plunged to $54 million for all of last year from $315.3 million in 1980, while 1981 revenue of $8.005 billion fell slightly from the record $8.011 billion reported for 1980.

RCA reported a loss equivalent to 19 cents a share in 1981, assuming the exercise of certain stock options and after deducting dividends on outstanding preferred stock. That compared with earnings of $3.35 a share in 1980.

RCA did not disclose figures for the operations of its units, but Ryan estimated a $100 million loss in 1981 from the video disc unit, predicting a $75 million loss in 1982 and a loss about half that amount in 1983.

RCA reported retail sales of 65,000 VideoDisc players in 1981 and said it will "monitor carefully" the progress of the operation. The company had hoped to sell 200,000 of the devices last year. But Bradshaw said consumer purchases of video albums to be played on the machines had exceeded expectations.

Bethlehem said fourth-quarter income was $31.1 million (71 cents a share) compared with $55.8 million ($1.28) in the 1980 quarter. Sales slipped to $1.64 billion from $1.7 billion.

For the year, income was $211 million ($4.83), compared with $121 million ($2.77) in 1980. Sales in 1981 totaled $7.3 billion, up from $6.7 billion the previous year.

Most steel companies have reported sharply reduced shipments in the last quarter of 1981, and Bethlehem was no exception. Shipments totaled 2.43 million tons, down from 2.83 million tons a year earlier. Steel shipments for the year were 11.57 million, up from 11.08 million tons in 1980.

Steel production for the quarter totaled 4.04 million tons, up from 3.72 million tons in 1980, while production for the year totaled 16.72 million tons, up from 15 million tons in 1980.

Trautlein noted that the company's steel shipments were higher in the second half and added that "we expect the reverse for 1982. He forecast steel industry shipments of about 87 million tons in 1982, about the same as 1981.

He said he also expects Bethlehem to sustain an operating loss in the first quarter of 1982 because of "low shipment levels, operating problems caused by severe winter weather and two recent fires at our Burns Harbor plant."

"We hope to see a modest improvement in Bethlehem's results in the second quarter," he added.

Philip Morris Inc. reported a 17.2 percent gain in earnings for 1981 on a 10.8 percent rise in sales, with profits for the fourth quarter up 11.1 up from $404.5 million ($4.22). Revenue grew to $6.38 billion from $4.87 billion. up from $404.5 million ($4.22). Revenue grew to $6.38 billion from $4.87 billion. percent on a 6.3 percent sales rise.

Net income for the year was $676.2 million ($5.41 a share) on revenues of $10.886 billion, compared with $576.8 million ($4.63) in 1980 on revenues of $9.882 billion. Fourth-quarter net income was $150.4 million ($1.20) on revenues of $2.573 billion, up from $135.4 million ($1.09) a year earlier on revenues of $2.42 billion.

Chairman George Weissman said cigarettes again were the big contributor to sales and earnings.