My knowledge of the stargazer package is limited but does this get the result you want? (note the change from stargazer(mod) to stargazer(mod, type = 'html')
---
output: slidy_presentation
---
## Regression Table
```{r echo=TRUE}
mod<-lm(temperature~pressure, data=pressure)
```
## stargazer table
```{r results='asis'}
library(stargazer)
stargazer(mod, type = 'html')
```
For me, the table renders as: