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If your site hasn't bad reputation and you have no problem into help increase the authority of the site you link to, AND:

1. The sites belongs to your niche: do follow.

2. You trust in their SEO practices and you think they are not penalized by Google: do follow.

If is your competitor or you are not interested into help them earn authority and rank: no follow.

If the site is not related at all with your content (for example you just want to promote other sites, profiles or platforms you own): no follow.

Make look the links natural, specially do follow ones. Be careful using the keyword on it's own in the anchor text.

I hope it helps.

Listen, the robots are so smart, so if you made it natural, without forcing, then they will know it, no worries.

You can also use some synonyms for the keyword.

Anyways if you're still worried there are SEO analyzers out there that can check your text for free. I don't want to put links here but they are so easy to find. Just type on Google.

Hope it helps