Cookie consent
Google Sites specialist Steegle has posted the following in respect to Cookie Consent requirements:
The EU has said specifically that a notice about non-privacy intrusive cookies used for tracking visits is no longer necessary
The so called "cookie provision", which has resulted in an overload of consent requests for internet users, will be streamlined. New rules will allow users to be more in control of their settings, providing an easy way to accept or refuse the tracking of cookies and other identifiers in case of privacy risks. The proposal clarifies that no consent is needed for non-privacy intrusive cookies improving internet experience (e.g. to remember shopping cart history). Cookies set by a visited website counting the number of visitors to that website will no longer require consent.
See: http://europa.eu/rapid/press-release_IP-17-16_en.htm
Using new Google Sites, you cannot add any technologies that use cookies that track personal data so you do not need anything.
If your site uses a domain that's based in the EU, e.g. .co.uk .de, etc then new Google Sites displays one automatically. If you don't use one of these domains or need/wish to add a cookie consent notice, this website provides a wizard to generate one. (see example below)