Hi Dmitri,
Thank you for your update.
At present we do not have support to insert rich text into
PDF document. A support incident to track the status of this feature has been
created under your account. Please log on to our support website to check for
further updates.
https://www.syncfusion.com/account/login?ReturnUrl=%2fsupport%2fdirecttrac%2fincidents
Please let us know if you need any further assistance.
Regards,
George