Rebecca Wood used a false name to phone the police with friend Johanna Low and the pair, both 17, claimed Andrew Walton tried to rape them at his home in East Wemyss.
Police officers were dispatched to the address and found Mr Walton at home with his mother but no sign of any girls.
At Cupar Sheriff Court, they were warned they would have been sent to detention had the investigation gone further.
Both admitted making a false report to police of attempted rape.
The offence was committed in the vicinity of Tentsmuir Forest on June 8 using a mobile phone.
Wood, of Methilhaven Road, Methil, was ordered to undertake 160 hours of community service and Low, of Nelson Street, Tayport, 135 hours.
Depute fiscal Shona McJannett told the court that Tayside Police received the call about 9.20pm and a female claimed Mr Walton had dragged her into his home and was trying to rape her.
A second female voice was also heard and both, who claimed they were sisters, said they were being attacked.
When the police arrived at Mr Walton's home, his mother identified the number of the phone which was used to make the call as belonging to Wood.
Both girls, first offenders, were under the influence of alcohol but the court was told they had since stopped drinking.
Wood's solicitor said her reaction to the argument showed immaturity of judgment and added, "She gave little thought to the consequences of the allegations she was making.
"Miss Wood accepts it was very lucky that the investigation did not go further."
Low claimed she did not know her friend was talking to the police but accepted later the call could not have been to anyone else.
He solicitor said, "The telephone call was made by her co-accused but Miss Low shouted comments of support from the background."
Sheriff Charles Macnair told the pair the perception that evidence of rape victims would not be accepted in court was made worse by false allegations.
"False allegations merely stoke prejudices in relation to what is an extremely serious offence," the sheriff told them.
"Where there are false allegations, they must be dealt with seriously.
"If there had been a serious investigation in relation to Andrew Walton, I would have had no hesitation even for first offenders in sentencing you to a period of detention."