Font for Thai Language - invoice template looks good, but pdf is missing the Thai text

Font for Thai Language - invoice template looks good, but pdf is missing the Thai text

Dear Ladies and Gents, 

i am using zoho books for a long time now. As my company is located in Bangkok, Thailand i need to write invoices 
also including Thai text. I can setup a template for invoices easily containg thai text. As soon as i go to print the thai text dissapears. Is there any chance to import different PDF fonts? All available fonts do European languagey, Japanes, Chinese and so on. But i cant find a font which also prints the Thai tex. Thanks a lot, Egils

As example i attached the zohobooks invoice template which is fine and the pdf which then is missing the thai descriptors