The Gordon and Buchan Reform candidate is the latest party hopeful to admit they voted in favour of independence in 2014.
Kris Callander said in an interview he had not always been a “hardline unionist”.
Appearing on the BBC Radio Scotland, Mr Callander was asked whether his party could be more “flexible” on the constitutional question.
He said: “I think we’re very much part of the UK, and we see Scotland as part of the UK.
‘It’s not like I’ve always been a hard-line unionist’
“I say that as someone who voted for independence in 2014. So it’s not like I’ve always been a hard-line unionist on this matter.”
He is the second of Mr Farage’s candidates to admit supporting Scotland’s exit from the UK after it was revealed Reform’s candidate in Dundee branded the 2014 ballot “corrupt”.
Party chairman Richard Tice said he did not know how many of the candidates endorsed by Reform had voted Yes in 2014.
He added: “If you live in a democracy, you need to practise democracy.
“You need to accept the result, otherwise you’re not practising the democracy you’re claiming to live in.”
The Tories are locked in a desperate war with Reform for votes as the party fears Mr Farage’s party could cost them seats to the SNP.
Key constituencies such as Gordon and Buchan could come down to the wire between the Conservatives and the SNP.
Reform chairman Mr Tice said on Wednesday he doesn’t care if his party’s candidates cost the Conservative seats – or if he scuppers the hopes of outgoing Tory leader Douglas Ross in Aberdeenshire North and Moray East.
The Tories claimed Reform was putting forward candidates in Scotland without properly checking their past views.
North East MSP Douglas Lumsden said: “Pro-UK voters will be dismayed by this astonishing admission from Reform’s candidate in Gordon and Buchan.
“It is clear that in key seats like Gordon and Buchan and up and down Scotland, Reform have put forward candidates without any idea of their views or voting history.
“Richard Tice even admitted this week he doesn’t know how many of his candidates in Scotland support independence, but we know several do.”
Gordon and Buchan candidate Mr Callander had previously came under fire for liking a page which claimed Dundee is full of people who have Aids.
Reform UK has been approached for comment.
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