St Kilda have signed former Adelaide ruckman Paul Hunter via the Supplemental Selection Period following star tall Rowan Marshall's pre-season foot injury.

Hunter has been training with St Kilda during the club's preparations for the 2021 season and will now join Mason Wood in signing with the Saints via the SSP.

According to AFL.com.au, an impressive performance at the Saints' intra-club match on Thursday looks to have been what might have sealed a permanent deal at Moorabbin.

Standing at 200cm tall, Hunter is set to boost St Kilda's ruck stocks with Marshall set to miss the next month after scans revealed a hot spot in his foot earlier this week.

Hunter will join veteran ruckman Paddy Ryder and new recruit Shaun McKernan in gunning for opening-round minutes under coach Brett Ratten.

The 28-year-old was listed with the Crows for four seasons before being cut from West Lakes in 2019 without making a breakthrough into the senior side.

Hunter had signed with Williamstown ahead of the 2020 VFL season, which was eventually abolished due to the impacts of the COVID-19 pandemic.

The additions of Hunter and Wood leave St Kilda with just the one available list spot for the 2021 season, with no notable train-on players now at the club following Hunter's new deal.

AFL clubs will have until March 9 to sign players via the SSP or opt for the Mid-Season Rookie Draft on June 2.