Boldin told reporters: "We're still in the process of working through that. That is just a trust thing. I think the more you do it, the more the receiver comes through for you, the more you trust in him.
"Obviously, we haven't been in that many situations to where we could work on it. There have been times in practice where he's given me a chance and we completed them.
"As a receiver, my thought is, every time a quarterback throws the ball to you, the more you complete the pass the more confidence he'll have in you."
San Francisco are currently without their top wideout from last season after Michael Crabtree suffered a torn ACL earlier in the year.