Hello ifotomagic,
Can you confirm which version of ArtRage for iOS you have?
If you have ‘ArtRage’ (the last version was 2.4.0) then 100% will be the largest tool size you can get I think.
If you have ‘ArtRage Vitae Mobile Painting’ (current version 1.1.5) then you should be able to go up to 500%