As Bob already mentioned, this is not acceptable. It adds no value to the answer, distracts users, and could even be considered rude. It should definitely be edited out. If a user keeps including these snippets,
flag the post for moderator attention and we'll have a word with them.
What situations would recommending selecting an answer be acceptable?
In my personal opinion, I can only think of very few. Think about it: We want answers to be accepted when the OP has decided that this answer worked for them. Regardless of its score. So, the only situation when you could really ask the OP to accept an answer is when they explicitly say, "Thanks, this worked!" or similar.
And even then, I would check if the OP actually knows how to accept answers – look into their profile and check other questions (if any). If they already know the concept of accepting answers, there's no point in telling them again.
Also, let me repeat: Regardless of an answer's score. If an answer was voted up by the community but the OP didn't accept it, then why would you ask them to? Maybe the answer doesn't work for them, or it fails to explain something the OP really wanted to know, et cetera. In that case, you could politely ask the user if there's something missing in the answer or if they have any additional questions.
In all other cases, just leave it. Accepted answers are nice and all, but the +15 reputation shouldn't be the only reason to pester others into accepting answers. Same goes for whining about accept rate. You can tell a user to consider accepting answers if and only if their questions are sufficiently answered and they haven't responded to any requests on whether they're missing information in one of these answers (which would allow them to accept them).
To go a little further: Think about how often you've asked a question and then suddenly weren't even in the position to judge whether an answer is correct. I have often ran into the situation where I needed programming help for a project, but that project doesn't exist anymore – so while I probably got really helpful answers, I don't see why I'd need to accept any if I can't verify them.
So, to sum up: If you're unsure, just leave it. No one will be hurt from answers not being accepted. Give new users some time to get to know the site, and they'll eventually find out.