The pair bolster Karl Gormley's options in the striking department, having trained with Raiders this summer, featuring in pre season friendlies this season.
Krol scored 15 goals for Pershore Town last year, with one of them being against Raiders! Roland Krol, most recently of Pershore Town, was previously at Raiders before joining the plums.
Ex-West Brom Scholar Walker follows assistant Tyrone Henderson from Littleton, having scored 3 goals in 10 appearances after joining the Ton in January for his second spell. In his first stint at the club, he was a vocal point in saving the club from relegation. He has previously been on the books at West Brom, Stourbridge and Worcester City to name a few.