Do I have to say it is my referral link?

Yes. Anyone who earns on a recommendation has to say so where the recommendation is made. That is the rule for every referral and affiliate link, everywhere.

How

One line is enough: "That's my referral link, and I get a little back when you subscribe." Every piece in your kit already ends with it. Keep it in.

Why it helps you

It reads as honesty. People trust a recommendation more when the person making it is upfront, and an upfront recommendation converts better than a hidden one.