It's the first time Russian athletes have acknowledged breaching of anti-doping rules.
A statement on the federation's website named the athletes as hammer thrower Anna Bulgakova, 400m runner Antonina Krivoshapka, shot putter Yevgenia Kolodko, discus thrower Vera Ganeyeva and pole vaulter Dmitry Starodubtsev.
RusAF anti-doping coordinator Yelena Ikonnikova said it was the first time Russian athletes have acknowledged breaching of anti-doping rules.
"This is the first time when our athletes acknowledged the anti-doping rules violations and also the first case that concerns the re-examination of the previously taken samples," she told AFP by phone.
She added that more athletes who are currently under investigation may follow their lead to reduce possible sanctions from the world athletics ruling body IAAF.
"If the IAAF... offers such a simplified procedure to our athletes who are currently under investigation, more people may follow this example," she said.
Ikonnikova suggested the Russians' voluntary acknowledgement of their guilt could help reinstate the country's athletics federation, which has been barred by IAAF from international competition since November 2015.
"We hope that this may help the RusAF to improve its image," the RusAF anti-doping coordinator assumed.
"The IAAF usually send athletes the letter giving them the option of admitting their guilt and accepting the sanctions," Ikonnikova said, adding that this would usually result in a reduced ban.
"If an athlete accepts this offer, the IAAF then approves the decision, which can no longer be disputed (in court)."
Banned from international athletics in November 2015 after evidence emerged of state-sponsored doping Russia was barred from last year's Rio Olympics and will not be able to send a team to this year's World Championships in London in August.
But 12 individual athletes have been allowed to compete as neutrals.