PO report Signature

Hi,
Iam working on PO Report rtf have a requirement to print signatures on rtf on left side and right side.Left side signature should be buyer and right side signature should be printed based on below conditions.Right now iam able to print buyer signature dynamically on left side.But not able to do with below conditions to display on right side.All the images are in OA_media path

if PO amt = < $2K and if buyer is  one group of users (‘G peter’,’N Jack’,’S charles’,)  then i should get supervisor's 'XXXX' signature.jpg,

and one more condition is