Hi Jonathan,
Thank you for contacting Syncfusion Support.
At present we do not have support for Electronic Invoice Specification, ZUGFeRD in PDF documents. We have logged a feature request and added it to our feature request list. We do not have any immediate plans to implement this feature. We will let you know once the feature is implemented.
Please let us know if you have any further assistance on this.
Regards,
Sowmiya L