The authenticity of a signature can only be verified in person. If you wish to officially verify your signature on a document, you must present a valid passport or national ID (or its digital equivalent in the eDoklady application). 

The authenticity of a signature cannot be verified on a blank document. 

The legalisation of the signature bears no relevance as far as  accuracy or truthfulness of the content of the document or its compliance with legal regulations. The Cosulate General is not responsible for the content of the document.