Its net loss for 2016 came in at £6.95 billion ($8.7 billion, 8.2 billion euros), up from a loss after tax of £1.98 billion a year earlier.
RBS, bailed-out by the British government following the 2008 financial crisis, posted its ninth consecutive annual losses last year.
Its net loss for 2016 came in at £6.95 billion ($8.7 billion, 8.2 billion euros), up from a loss after tax of £1.98 billion a year earlier, RBS said in a statement.
"There will be job losses that we will have to go through to get this business back into shape," said chief executive Ross McEwan, who would not be drawn on an exact figure.
The Edinburgh-based lender said it had been hit by litigation and conduct costs of almost £5.9 billion, largely over its role in the 2008 US subprime housing crisis.
It suffered also restructuring charges totalling £2.1 billion during 2016.
"These costs are a stark reminder of what happens to a bank when things go wrong and you lose focus on the customer, as this bank did before the financial crisis," added New Zealand national McEwan.
RBS is around 73-percent owned by the British government after the lender was saved with £45.5 billion of taxpayers' cash in the world's biggest banking bailout at the height of the global financial crisis.
It has meanwhile reported total losses of around £60 billion since the state rescue.
In recent years, McEwan has overseen a massive overhaul of operations, slashing the bank's investment banking activities and axing tens of thousands of jobs.
On Friday, RBS said it would slash operating expenses by a further £2 billion over four years, with £750 million of savings being made in 2017.
RBS is setting aside £6.7 billion to cover potential US fines over the alleged mis-selling of mortgage securities that precipitated the 2008 global financial meltdown.
The system-wide failure in 2008 of complex securities derived from residential mortgages caused a cascading wave of bankruptcies and crises that sparked a global recession, leading to tens of millions of job losses around the world.
RBS joins several banks implicated in the global financial crisis, including Barclays, Deutsche Bank and Credit Suisse.
"The past is not completely behind us, with our dealings on residential mortgage backed securities and Williams & Glyn... two significant issues that we still need to resolve," McEwan added on Friday.
RBS has made four of the five major divestments demanded by the European Commission in 2009 to address competition concerns following its bailout, but has struggled to offload its Williams & Glyn unit.
In a bid to address the problem, the British government last week proposed plans for RBS to fund initiatives worth £750 million to help small UK lenders win business.
In trading Friday, RBS shares slid 3.4 percent to 240.90 pence on London's benchmark FTSE 100 index, which was down 0.6 percent overall at 7,230.53 points nearing midday in the capital.
The situation at RBS is in sharp contrast to Lloyds Banking Group -- another UK lender rescued with taxpayers' money following the financial crisis -- which is both profitable and close to a full return to the private sector.
Results from RBS cap the annual earnings season for Britain's major banks, which are facing uncertain times also as the country prepares for Brexit.
Barclays on Thursday said it returned to profit after slashing provisions set aside for legal and compensation costs linked to foreign exchange and insurance scandals.
But profits at HSBC have plunged on huge writedowns and restructuring charges, while it warned this week of uncertainty over Brexit and Donald Trump's economic policies.