21 year old Rayner is still registered with League of Wales club Port Talbot but has spent the last few weeks on trial with the Imps as Keith attempts to provide cover for Alan Marriott. Its expected any paperwork will merely be a formality.
Rayner recently had a trial at Swansea City and was given his chance last Thursday when a young Imps side went down 3-0 at King's Lynn. It was also reported he enjoyed a trial spell with Newcastle United back in April of last year. He has also been linked with FA Cup finalists Millwall.
The 6ft 3in keeper impressed despite the scoreline against Kings Lynn and earned a further appearance against Forest on Saturday.
"Simon has been training with us for a few days now," said Keith Alexander. "He did very well at King's Lynn and I think he's what we've been looking for. He's just a young lad, but big and strong. We need someone who can put pressure on Mazza."
Rayner has appeared for Canada at youth, Under 21 and Under 23 level and will be hoping to add a full cap to his current collection. He spent two seasons at Bournemouth, before joining Barry Town and then Port Talbot.