Moore has joined up with the rest of the team in Austria after joining the Millers on a season long loan deal.
Speaking to the clubs official website, boss Paul Warne said; "We are delighted to bring Kieffer into the club, He played against us last year and did well. We spoke to a few people about him and it was all good news. He has got some amazing attributes. He is really keen and ready to learn. He is very athletic and very strong and it is another striker to add to our attacking force."
"Kieffer's arrival now gives us more options. I have always said the more strikers and the more competition I can get up front the better. He will play a part in the game tomorrow night and I look forward to seeing how he shapes up."
"I am really happy that he decided to come to us, he has come out to Austria and he has got on with the lads straight away, He flew straight out here from Dublin to join up with us, where he played for Ipswich and scored for them on Saturday. I really liked him when I saw him play and when I met him I liked his attitude. He is another positive kid to have around the place. He wants to come here and help us, he has plenty of ability and I really like the way we are shaping up now up top."