This is just a thought for the future.
When sending out Tenancy Deposit Details including the terms and conditions of the scheme - I use the method of posting via post office and obtaining cert of posting.
My TDS paperwork which I download from the TDS site, requires the tenant to sign the paperwork.
What happens if you can't get the tenant to sign? My last tenant just wouldn't co-operate - he ended up asking me to evict him and then I said, I couldn't go through the process until he signed the TDS document. Because he wanted something - he signed the form.
I can't see any legal comeback so long as I know everything has been deposited correctly and the tenants have received all the required information. Am I wrong?