The wording “The holder is not required to sign” will be shown in the passport where the signature would normally be.
If you apply online
You’ll be asked if you can sign your passport during your application. Explain why you cannot sign and send supporting evidence.
If you apply using a paper form
You can get someone to sign the form on your behalf (such as a relative, social services officer or doctor) if your disability means you cannot sign the form yourself - for example you cannot write, or have learning or writing difficulties.
They should sign the declaration and give an explanation of why you cannot sign in both:
section 8 of the form
a covering letter that they’ve signed and dated