Design an RFID UHF 868Mhz antenna for handheld device

We have developed an portable battery-powered device which include an RFID UHD module of Ray-Links (module RLM060). We have failed integrating a ready-to-marked little smd antenna, so we need a custom (pcb?) antenna design to match with our reader. Fortunately, when we designed the electronic board, we keep RFID UHF section in a small separated pcb, in order to keep modifications to that side of the board separated from the main logic. I put here a couple of images of the small PCB on which we put the RFID module and the antenna smd. The job is to entirely redesign that part of the board, composed of few components (the RFID RLM060 module itself and the antenna). Our goal is to have a design that match theese requirements: 1.) 71x14 mm six layer PCB with RLM060 and antenna (eventually dimensions can slightly change) cirular RFID antenna, centered on ETSI 868 MHZ RFID UHF BAND 2.) reading field up to 12 cm (now we can read tags only to few centimeters and only in particular orientation) 3) Time: time requirements are strict. I'm looking for an engineer with proven experience in microwave and RFID UHF antenna design. Once we will decide to work together, we can make a Skype call and discuss jobs details and value. All technical details will be shared after this preliminary phase.