You may take advantage of the PDF templates provided by the SuiteApp. These templates include the mandatory information.
[STA] Latvia Invoice PDF/HTML Template
[STA] Latvia Credit Memo PDF/HTML Template
These templates can be used as a template or can be assigned to an existing transaction form.
Important: These templates should not be modified. There is a chance that the changes that were made will be lost during bundle update.
To modify a transaction form and assign the PDF layout:
Go to Customization > Forms > Transaction Forms
Click Edit next to the transaction form.
On the PDF Layout drop-down field, select the template.
Click the Save As button.