How to display field of related ID in HTML Template

Hi Everyone,

I have requirement to create html template and display some fields. Most of the fields is sucess to displayed in html template, but i want to display related records,

for example i have incident ticket IMXXX and that related with SDXXX, i want to display SDXXX in html template.

I have tried to call that field like this {$RECORD.relatedId} but it does not work.

Could you please let me know for do that?
Appreciate if you give me some help :)

Best Regards,
Okik