Three men threatened staff and stole around £1,500 from the KFC in Goring at closing time on Sunday, police said.
Police said three men entered the restaurant in Goring Road, Goring, at about 10.30pm on Sunday (November 4).
They threatened staff and stole the takings, about £1500, before making off on foot eastwards towards Worthing, police said.
No weapons were seen but one member of staff was assaulted – though not physically injured, police confirmed.
All four staff members were left ‘shocked and upset’ by what happened, according to police.
There were no customers present at the time.
Police describe the three suspects as black, in their early to mid-twenties, with masks or scarves over faces, wearing puffa and parka jackets and tracksuit bottoms.
Detective Constable Pete Parkinson said: “If you saw what happened or have any other information please contact us online or by calling 101, quoting serial 1245 of 04/11.
“Alternatively, you can visit the Crimestoppers website or contact the independent charity anonymously on 0800 555 111.”