That particular diagram for DC Voltage Source is a PMComponent from the Simscape -> Electrical -> Specialized Power Systems -> Fundamental Blocks -> Electrical Sources library. You can tell because all of the other DC Voltage Source that I could find incorporate a circle as part of the design element, whereas the design for that particular element is similar to those of batteries. The port type is 'p1'.
The DC Voltage Source itself is compatible with the '1' input of Ideal Switch, which is from Simscape -> Electrical -> Specialized Power Systems -> Fundamental Blocks -> Power Electronics and is also a 'p1' port.
However, no-where in Specialized Power Systems is there a resistor as such -- or a capacitor as such.
There is Simscape -> Electrical -> Electriconics and Mechatronics -> Passive Devices -> Resistor, and Capacitor, but those are both Simscape Block, which is not a matching type.
To get anywhere you have a small number of choices:
1) Create custom blocks within powersysdomain; or
2) Move out of Specialized Power Systems into a different domain. This would probably block you from using Ideal Switch
3) Use Sebastian's idea of using an RLC related block (he posted while I was in the middle of investigating and composing)
I do not know if there is a fourth option of somehow creating an adaptor between domains.
