When I feed dry worms, I take a pinch between my fingers, submerge it, and squeeze out the air. Most sink, the tetras seem to like hunting the remaining "floaters."
feeding the fish straight frozen bloodworms can be dangerous to their health. it is a literal shock to their system coming from the inside. fish are cold blooded, so if the frozen bloodworms are eaten up by the fish, they have the cold bloodworms on the inside, and warm tank water on the outside, resulting in a pretty large temp difference for a while until everything evens out.
I personally don't soak the freeze dried ones, but I also rarely feed them to my fish. Its mostly just an occasional treat. I put a small pinch in the tank and enjoy watching my tetras and rasboras chase the pieces around. I use frozen much more often than freeze dried, and as most others have suggested with frozen, I thaw them first then slowly add them to the tank while the fish swarm the cloud 'o worms and munch them down. If you're really worried about the fish getting air in their swim bladder, I'm sure it'd only take a few minutes to soak some freezedried ones in a cup and then spoon them in, but in that case, wouldn't it be easier to just go with frozen rather than freeze dried?