How to Mail Merge with Dynamic Images

How to Mail Merge with Dynamic Images

Hello

Im trying to update a mail merge letter so that each letter has an different image pulled into it for the specific recipient record.

The images filenames are all named as a specific zoho record reference number (e.g.REF1.jpg, REF2.jpg, REF3.jpg....) I thought i would upload all the images to WorkDrive or something similar and then call this dynamically based on the REF field in the Zoho record. 

Im not very experienced in this area so would appreciate some advice on the best way to achieve this?

Many thanks!