The patches seem to work OK for some, and not at all for others, so let your labs be the judge as to whether they work for you, and whether you need to supplement with something else. From what I have seen, most in the DS world find that they don't work at all for them, but there may be something about their altered metabolism at work there that doesn't apply to us with the VSG.
For some nutrients, deficiencies aren't easy to detect until things are pretty low, and it can be hard to catch up if you fall behind the curve, so I would be cautious about depending upon the patches totally. For instance, I would maybe try them for part my calcium needs, using the patch instead of the extra dose or two per day of calcium that we usually need early out, but still take at least one dose with the pills or chewies. OTOH. the iron numbers measure out pretty easily, and we can usually catch up by doubling the dose if need be (something that the bypass folks have a harder time doing with their malabsorption) so that can be a good indicator as to whether the patches work for you.